<s>
IBM	O
CICS	B-Application
(	O
Customer	B-Application
Information	I-Application
Control	I-Application
System	I-Application
)	O
is	O
a	O
family	O
of	O
mixed-language	O
application	O
servers	O
that	O
provide	O
online	O
transaction	B-General_Concept
management	O
and	O
connectivity	O
for	O
applications	O
on	O
IBM	B-Device
mainframe	I-Device
systems	O
under	O
z/OS	B-Application
and	O
z/VSE	B-Application
.	O
</s>
<s>
CICS	B-Application
family	O
products	O
are	O
designed	O
as	O
middleware	B-General_Concept
and	O
support	O
rapid	O
,	O
high-volume	O
online	B-General_Concept
transaction	I-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
A	O
CICS	B-Application
transaction	B-General_Concept
is	O
a	O
unit	O
of	O
processing	O
initiated	O
by	O
a	O
single	O
request	O
that	O
may	O
affect	O
one	O
or	O
more	O
objects	O
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
(	O
CICS	B-Application
TS	O
)	O
sits	O
at	O
the	O
head	O
of	O
the	O
CICS	B-Application
family	O
and	O
provides	O
services	O
that	O
extend	O
or	O
replace	O
the	O
functions	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
These	O
services	O
can	O
be	O
more	O
efficient	O
than	O
the	O
generalized	O
operating	B-Operating_System
system	I-Operating_System
services	I-Operating_System
and	O
also	O
simpler	O
for	O
programmers	O
to	O
use	O
,	O
particularly	O
with	O
respect	O
to	O
communication	O
with	O
diverse	O
terminal	O
devices	O
.	O
</s>
<s>
Applications	O
developed	O
for	O
CICS	B-Application
may	O
be	O
written	O
in	O
a	O
variety	O
of	O
programming	O
languages	O
and	O
use	O
CICS-supplied	O
language	O
extensions	O
to	O
interact	O
with	O
resources	O
such	O
as	O
files	O
,	O
database	B-General_Concept
connections	I-General_Concept
,	O
terminals	O
,	O
or	O
to	O
invoke	O
functions	O
such	O
as	O
web	O
services	O
.	O
</s>
<s>
CICS	B-Application
manages	O
the	O
entire	O
transaction	B-General_Concept
such	O
that	O
if	O
for	O
any	O
reason	O
a	O
part	O
of	O
the	O
transaction	B-General_Concept
fails	O
all	O
recoverable	O
changes	O
can	O
be	O
backed	O
out	O
.	O
</s>
<s>
While	O
CICS	B-Application
TS	O
has	O
its	O
highest	O
profile	O
among	O
large	O
financial	O
institutions	O
,	O
such	O
as	O
banks	O
and	O
insurance	O
companies	O
,	O
many	O
Fortune	O
500	O
companies	O
and	O
government	O
entities	O
are	O
reported	O
to	O
run	O
CICS	B-Application
.	O
</s>
<s>
Other	O
,	O
smaller	O
enterprises	O
can	O
also	O
run	O
CICS	B-Application
TS	O
and	O
other	O
CICS	B-Application
family	O
products	O
.	O
</s>
<s>
CICS	B-Application
can	O
regularly	O
be	O
found	O
behind	O
the	O
scenes	O
in	O
,	O
for	O
example	O
,	O
bank-teller	O
applications	O
,	O
ATM	O
systems	O
,	O
industrial	O
production	O
control	O
systems	O
,	O
insurance	O
applications	O
,	O
and	O
many	O
other	O
types	O
of	O
interactive	O
applications	O
.	O
</s>
<s>
Recent	O
CICS	B-Application
TS	O
enhancements	O
include	O
new	O
capabilities	O
to	O
improve	O
the	O
developer	O
experience	O
,	O
including	O
the	O
choice	O
of	O
APIs	O
,	O
frameworks	O
,	O
editors	O
,	O
and	O
build	O
tools	O
,	O
while	O
at	O
the	O
same	O
time	O
providing	O
updates	O
in	O
the	O
key	O
areas	O
of	O
security	O
,	O
resilience	O
,	O
and	O
management	O
.	O
</s>
<s>
In	O
earlier	O
,	O
recent	O
CICS	B-Application
TS	O
releases	O
,	O
support	O
was	O
provided	O
for	O
Web	O
services	O
and	O
Java	B-Language
,	O
event	B-Operating_System
processing	I-Operating_System
,	O
Atom	B-Application
feeds	I-Application
,	O
and	O
RESTful	B-Protocol
interfaces	I-Protocol
.	O
</s>
<s>
CICS	B-Application
was	O
preceded	O
by	O
an	O
earlier	O
,	O
single-threaded	B-Operating_System
transaction	B-General_Concept
processing	O
system	O
,	O
IBM	B-Application
MTCS	I-Application
.	O
</s>
<s>
An	O
'	O
MTCS-CICS	O
bridge	O
 '	O
was	O
later	O
developed	O
to	O
allow	O
these	O
transactions	O
to	O
execute	O
under	O
CICS	B-Application
with	O
no	O
change	O
to	O
the	O
original	O
application	O
programs	O
.	O
</s>
<s>
IBM	O
's	O
Customer	B-Application
Information	I-Application
Control	I-Application
System	I-Application
(	O
CICS	B-Application
)	O
,	O
first	O
developed	O
in	O
conjunction	O
with	O
Michigan	O
Bell	O
in	O
1966	O
.	O
</s>
<s>
CICS	B-Application
was	O
originally	O
developed	O
in	O
the	O
United	O
States	O
out	O
of	O
the	O
IBM	O
Development	O
Center	O
in	O
Des	O
Plaines	O
,	O
Illinois	O
,	O
beginning	O
in	O
1966	O
to	O
address	O
requirements	O
from	O
the	O
public	O
utility	O
industry	O
.	O
</s>
<s>
The	O
first	O
CICS	B-Application
product	O
was	O
announced	O
in	O
1968	O
,	O
named	O
Public	O
Utility	O
Customer	B-Application
Information	I-Application
Control	I-Application
System	I-Application
,	O
or	O
PU-CICS	O
.	O
</s>
<s>
It	O
became	O
clear	O
immediately	O
that	O
it	O
had	O
applicability	O
to	O
many	O
other	O
industries	O
,	O
so	O
the	O
Public	O
Utility	O
prefix	O
was	O
dropped	O
with	O
the	O
introduction	O
of	O
the	O
first	O
release	O
of	O
the	O
CICS	B-Application
Program	O
Product	O
on	O
July	O
8	O
,	O
1969	O
,	O
not	O
long	O
after	O
IMS	B-Application
database	B-Application
management	I-Application
system	I-Application
.	O
</s>
<s>
For	O
the	O
next	O
few	O
years	O
,	O
CICS	B-Application
was	O
developed	O
in	O
Palo	O
Alto	O
and	O
was	O
considered	O
a	O
less	O
important	O
"	O
smaller	O
"	O
product	O
than	O
IMS	B-Application
which	O
IBM	O
then	O
considered	O
more	O
strategic	O
.	O
</s>
<s>
When	O
IBM	O
decided	O
to	O
end	O
development	O
of	O
CICS	B-Application
in	O
1974	O
to	O
concentrate	O
on	O
IMS	B-Application
,	O
the	O
CICS	B-Application
development	O
responsibility	O
was	O
picked	O
up	O
by	O
the	O
IBM	O
Hursley	O
site	O
in	O
the	O
United	O
Kingdom	O
,	O
which	O
had	O
just	O
ceased	O
work	O
on	O
the	O
PL/I	B-Language
compiler	B-Language
and	O
so	O
knew	O
many	O
of	O
the	O
same	O
customers	O
as	O
CICS	B-Application
.	O
</s>
<s>
CICS	B-Application
originally	O
only	O
supported	O
a	O
few	O
IBM-brand	O
devices	O
like	O
the	O
1965	O
IBM	O
2741	O
Selectric	O
(	O
golf	O
ball	O
)	O
typewriter-based	O
terminal	O
.	O
</s>
<s>
The	O
1964	O
IBM	B-Device
2260	I-Device
and	O
1972	O
IBM	B-Operating_System
3270	I-Operating_System
video	B-General_Concept
display	I-General_Concept
terminals	I-General_Concept
were	O
widely	O
used	O
later	O
.	O
</s>
<s>
In	O
the	O
early	O
days	O
of	O
IBM	B-Device
mainframes	I-Device
,	O
computer	O
software	O
was	O
free	O
bundled	O
at	O
no	O
extra	O
charge	O
with	O
computer	B-Architecture
hardware	I-Architecture
.	O
</s>
<s>
The	O
OS/360	B-Application
operating	B-General_Concept
system	I-General_Concept
and	O
application	O
support	O
software	O
like	O
CICS	B-Application
were	O
"	O
open	O
"	O
to	O
IBM	O
customers	O
long	O
before	O
the	O
open-source	B-Application
software	I-Application
initiative	O
.	O
</s>
<s>
Corporations	O
like	O
Standard	O
Oil	O
of	O
Indiana	O
(	O
Amoco	O
)	O
made	O
major	O
contributions	O
to	O
CICS	B-Application
.	O
</s>
<s>
The	O
IBM	O
Des	O
Plaines	O
team	O
tried	O
to	O
add	O
support	O
for	O
popular	O
non-IBM	O
terminals	O
like	O
the	O
ASCII	B-Protocol
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
,	O
but	O
the	O
small	O
low-budget	O
software	O
development	O
team	O
could	O
not	O
afford	O
the	O
$	O
100-per-month	O
hardware	B-Architecture
to	O
test	O
it	O
.	O
</s>
<s>
IBM	O
executives	O
incorrectly	O
felt	O
that	O
the	O
future	O
would	O
be	O
like	O
the	O
past	O
,	O
with	O
batch	B-General_Concept
processing	I-General_Concept
using	O
traditional	O
punch	B-Architecture
cards	I-Architecture
.	O
</s>
<s>
IBM	O
reluctantly	O
provided	O
only	O
minimal	O
funding	O
when	O
public	O
utility	O
companies	O
,	O
banks	O
and	O
credit-card	O
companies	O
demanded	O
a	O
cost-effective	O
interactive	O
system	O
(	O
similar	O
to	O
the	O
1965	O
IBM	B-Application
Airline	I-Application
Control	I-Application
Program	I-Application
used	O
by	O
the	O
American	O
Airlines	O
Sabre	B-Application
computer	B-Application
reservation	I-Application
system	I-Application
)	O
for	O
high-speed	O
data	O
access-and-update	O
to	O
customer	O
information	O
for	O
their	O
telephone	O
operators	O
(	O
without	O
waiting	O
for	O
overnight	O
batch	B-General_Concept
processing	I-General_Concept
punch	B-Architecture
card	I-Architecture
systems	O
)	O
.	O
</s>
<s>
When	O
CICS	B-Application
was	O
delivered	O
to	O
Amoco	O
with	O
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
support	O
,	O
it	O
caused	O
the	O
entire	O
OS/360	B-Application
operating	B-General_Concept
system	I-General_Concept
to	O
crash	O
(	O
including	O
non-CICS	O
application	O
programs	O
)	O
.	O
</s>
<s>
The	O
majority	O
of	O
the	O
CICS	B-Application
Terminal	O
Control	O
Program	O
(	O
TCP	O
the	O
heart	O
of	O
CICS	B-Application
)	O
and	O
part	O
of	O
OS/360	B-Application
had	O
to	O
be	O
laboriously	O
redesigned	O
and	O
rewritten	O
by	O
Amoco	O
Production	O
Company	O
in	O
Tulsa	O
Oklahoma	O
.	O
</s>
<s>
In	O
a	O
few	O
years	O
,	O
CICS	B-Application
generated	O
over	O
$60	O
billion	O
in	O
new	O
hardware	B-Architecture
revenue	O
for	O
IBM	O
,	O
and	O
became	O
their	O
most-successful	O
mainframe	O
software	O
product	O
.	O
</s>
<s>
In	O
1972	O
,	O
CICS	B-Application
was	O
available	O
in	O
three	O
versions	O
DOS-ENTRY	O
(	O
program	O
number	O
5736-XX6	O
)	O
for	O
DOS/360	B-Application
machines	O
with	O
very	O
limited	O
memory	B-General_Concept
,	O
DOS-STANDARD	O
(	O
program	O
number	O
5736-XX7	O
)	O
,	O
for	O
DOS/360	B-Application
machines	O
with	O
more	O
memory	B-General_Concept
,	O
and	O
OS-STANDARD	O
V2	O
(	O
program	O
number	O
5734-XX7	O
)	O
for	O
the	O
larger	O
machines	O
which	O
ran	O
OS/360	B-Application
.	O
</s>
<s>
In	O
early	O
1970	O
,	O
a	O
number	O
of	O
the	O
original	O
developers	O
,	O
including	O
Ben	O
Riggins	O
(	O
the	O
principal	O
architect	O
of	O
the	O
early	O
releases	O
)	O
relocated	O
to	O
California	O
and	O
continued	O
CICS	B-Application
development	O
at	O
IBM	O
's	O
Palo	O
Alto	O
Development	O
Center	O
.	O
</s>
<s>
In	O
1980	O
,	O
IBM	O
executives	O
failed	O
to	O
heed	O
Ben	O
Riggins	O
 '	O
strong	O
suggestions	O
that	O
IBM	O
should	O
provide	O
their	O
own	O
EBCDIC-based	O
operating	B-General_Concept
system	I-General_Concept
and	O
integrated-circuit	O
microprocessor	B-Architecture
chip	O
for	O
use	O
in	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
as	O
a	O
CICS	B-Application
intelligent	B-Device
terminal	I-Device
(	O
instead	O
of	O
the	O
incompatible	O
Intel	O
chip	O
,	O
and	O
immature	O
ASCII-based	O
Microsoft	O
1980	O
DOS	B-Device
)	O
.	O
</s>
<s>
Because	O
of	O
the	O
limited	O
capacity	O
of	O
even	O
large	O
processors	O
of	O
that	O
era	O
every	O
CICS	B-Application
installation	O
was	O
required	O
to	O
assemble	O
the	O
source	O
code	O
for	O
all	O
of	O
the	O
CICS	B-Application
system	O
modules	O
after	O
completing	O
a	O
process	O
similar	O
to	O
system	B-Application
generation	I-Application
(	O
sysgen	B-Application
)	O
,	O
called	O
CICSGEN	O
,	O
to	O
establish	O
values	O
for	O
conditional	O
assembly-language	O
statements	O
.	O
</s>
<s>
This	O
process	O
allowed	O
each	O
customer	O
to	O
exclude	O
support	O
from	O
CICS	B-Application
itself	O
for	O
any	O
feature	O
they	O
did	O
not	O
intend	O
to	O
use	O
,	O
such	O
as	O
device	O
support	O
for	O
terminal	O
types	O
not	O
in	O
use	O
.	O
</s>
<s>
CICS	B-Application
owes	O
its	O
early	O
popularity	O
to	O
its	O
relatively	O
efficient	O
implementation	O
when	O
hardware	B-Architecture
was	O
very	O
expensive	O
,	O
its	O
multi-threaded	B-Operating_System
processing	O
architecture	O
,	O
its	O
relative	O
simplicity	O
for	O
developing	O
terminal-based	O
real-time	O
transaction	B-General_Concept
applications	O
,	O
and	O
many	O
open-source	B-Application
customer	O
contributions	O
,	O
including	O
both	O
debugging	O
and	O
feature	O
enhancement	O
.	O
</s>
<s>
Part	O
of	O
CICS	B-Application
was	O
formalized	O
using	O
the	O
Z	B-Language
notation	I-Language
in	O
the	O
1980s	O
and	O
1990s	O
in	O
collaboration	O
with	O
the	O
Oxford	O
University	O
Computing	O
Laboratory	O
,	O
under	O
the	O
leadership	O
of	O
Tony	O
Hoare	O
.	O
</s>
<s>
In	O
1986	O
,	O
IBM	O
announced	O
CICS	B-Application
support	O
for	O
the	O
record-oriented	O
file	O
services	O
defined	O
by	O
Distributed	B-Operating_System
Data	I-Operating_System
Management	I-Operating_System
Architecture	I-Operating_System
(	O
DDM	O
)	O
.	O
</s>
<s>
This	O
enabled	O
programs	O
on	O
remote	O
,	O
network-connected	O
computers	O
to	O
create	O
,	O
manage	O
,	O
and	O
access	O
files	O
that	O
had	O
previously	O
been	O
available	O
only	O
within	O
the	O
CICS/MVS	O
and	O
CICS/VSE	O
transaction	B-General_Concept
processing	O
environments	O
.	O
</s>
<s>
In	O
newer	O
versions	O
of	O
CICS	B-Application
,	O
support	O
for	O
DDM	O
has	O
been	O
removed	O
.	O
</s>
<s>
Support	O
for	O
the	O
DDM	O
component	O
of	O
CICS	B-Application
z/OS	B-Application
was	O
discontinued	O
at	O
the	O
end	O
of	O
2003	O
,	O
and	O
was	O
removed	O
from	O
CICS	B-Application
for	O
z/OS	B-Application
in	O
version	O
5.2	O
onward	O
.	O
</s>
<s>
In	O
CICS	B-Application
TS	O
for	O
z/VSE	B-Application
,	O
support	O
for	O
DDM	O
was	O
stabilised	O
at	O
V1.1.1	O
level	O
,	O
with	O
an	O
announced	O
intention	O
to	O
discontinue	O
it	O
in	O
a	O
future	O
release	O
.	O
</s>
<s>
In	O
CICS	B-Application
for	O
z/VSE	B-Application
2.1	O
onward	O
,	O
CICS/DDM	O
is	O
not	O
supported	O
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
first	O
introduced	O
a	O
native	O
HTTP	B-Protocol
interface	O
in	O
version	O
1.2	O
,	O
together	O
with	O
a	O
Web	O
Bridge	O
technology	O
for	O
wrapping	O
green-screen	O
terminal-based	O
programs	O
with	O
an	O
HTML	O
facade	O
.	O
</s>
<s>
CICS	B-Application
Web	O
and	O
Document	O
APIs	O
were	O
enhanced	O
in	O
CICS	B-Application
TS	O
V1.3	O
to	O
enable	O
web-aware	O
applications	O
to	O
be	O
written	O
to	O
interact	O
more	O
effectively	O
with	O
web	O
browsers	O
.	O
</s>
<s>
CICS	B-Application
TS	O
versions	O
2.1	O
through	O
2.3	O
focused	O
on	O
introducing	O
CORBA	B-Architecture
and	O
EJB	B-Language
technologies	O
to	O
CICS	B-Application
,	O
offering	O
new	O
ways	O
to	O
integrate	O
CICS	B-Application
assets	O
into	O
distributed	O
application	O
component	O
models	O
.	O
</s>
<s>
These	O
technologies	O
relied	O
on	O
hosting	O
Java	B-Language
applications	O
in	O
CICS	B-Application
.	O
</s>
<s>
The	O
Java	B-Language
hosting	O
environment	O
saw	O
numerous	O
improvements	O
over	O
many	O
releases	O
,	O
ultimately	O
resulting	O
in	O
the	O
embedding	O
of	O
the	O
WebSphere	B-Language
Liberty	I-Language
Profile	I-Language
into	O
CICS	B-Application
Transaction	I-Application
Server	I-Application
V5.1	O
.	O
</s>
<s>
Numerous	O
web	O
facing	O
technologies	O
could	O
be	O
hosted	O
in	O
CICS	B-Application
using	O
Java	B-Language
,	O
this	O
ultimately	O
resulted	O
in	O
the	O
removal	O
of	O
the	O
native	O
CORBA	B-Architecture
and	O
EJB	B-Language
technologies	O
.	O
</s>
<s>
CICS	B-Application
TS	O
V3.1	O
added	O
a	O
native	O
implementation	O
of	O
the	O
SOAP	B-Application
and	O
WSDL	O
technologies	O
for	O
CICS	B-Application
,	O
together	O
with	O
client	O
side	O
HTTP	B-Protocol
APIs	O
for	O
outbound	O
communication	O
.	O
</s>
<s>
These	O
twin	O
technologies	O
enabled	O
easier	O
integration	O
of	O
CICS	B-Application
components	O
with	O
other	O
Enterprise	O
applications	O
,	O
and	O
saw	O
widespread	O
adoption	O
.	O
</s>
<s>
Tools	O
were	O
included	O
for	O
taking	O
traditional	O
CICS	B-Application
programs	O
written	O
in	O
languages	O
such	O
as	O
COBOL	B-Application
,	O
and	O
converting	O
them	O
into	O
WSDL	O
defined	O
Web	O
Services	O
,	O
with	O
little	O
or	O
no	O
program	O
changes	O
.	O
</s>
<s>
This	O
technology	O
saw	O
regular	O
enhancements	O
over	O
successive	O
releases	O
of	O
CICS	B-Application
.	O
</s>
<s>
CICS	B-Application
TS	O
V4.1	O
and	O
V4.2	O
saw	O
further	O
enhancements	O
to	O
web	O
connectivity	O
,	O
including	O
a	O
native	O
implementation	O
of	O
the	O
Atom	B-Application
publishing	I-Application
protocol	I-Application
.	O
</s>
<s>
Many	O
of	O
the	O
newer	O
web	O
facing	O
technologies	O
were	O
made	O
available	O
for	O
earlier	O
releases	O
of	O
CICS	B-Application
using	O
delivery	O
models	O
other	O
than	O
a	O
traditional	O
product	O
release	O
.	O
</s>
<s>
Examples	O
include	O
the	O
Soap	B-Application
for	O
CICS	B-Application
technology	O
preview	O
SupportPac	O
for	O
TS	O
V2.2	O
,	O
or	O
the	O
ATOM	B-Application
SupportPac	O
for	O
TS	O
V3.1	O
.	O
</s>
<s>
This	O
approach	O
was	O
used	O
to	O
introduce	O
JSON	B-General_Concept
support	O
for	O
CICS	B-Application
TS	O
V4.2	O
,	O
a	O
technology	O
that	O
went	O
on	O
to	O
be	O
integrated	O
into	O
CICS	B-Application
TS	O
V5.2	O
.	O
</s>
<s>
The	O
JSON	B-General_Concept
technology	O
in	O
CICS	B-Application
is	O
similar	O
to	O
earlier	O
SOAP	B-Application
technology	O
,	O
both	O
of	O
which	O
allowed	O
programs	O
hosted	O
in	O
CICS	B-Application
to	O
be	O
wrapped	O
with	O
a	O
modern	O
facade	O
.	O
</s>
<s>
The	O
JSON	B-General_Concept
technology	O
was	O
in	O
turn	O
enhanced	O
in	O
z/OS	B-Application
Connect	O
Enterprise	O
Edition	O
,	O
an	O
IBM	O
product	O
for	O
composing	O
JSON	B-General_Concept
APIs	O
that	O
can	O
leverage	O
assets	O
from	O
several	O
mainframe	O
subsystems	O
.	O
</s>
<s>
Many	O
partner	O
products	O
have	O
also	O
been	O
used	O
to	O
interact	O
with	O
CICS	B-Application
.	O
</s>
<s>
Popular	O
examples	O
include	O
using	O
the	O
CICS	B-Application
Transaction	I-Application
Gateway	I-Application
for	O
connecting	O
to	O
CICS	B-Application
from	O
JCA	B-Language
compliant	O
Java	B-Language
application	O
servers	O
,	O
and	O
IBM	O
DataPower	O
appliances	O
for	O
filtering	O
web	O
traffic	O
before	O
it	O
reaches	O
CICS	B-Application
.	O
</s>
<s>
Modern	O
versions	O
of	O
CICS	B-Application
provide	O
many	O
ways	O
for	O
both	O
existing	O
and	O
new	O
software	O
assets	O
to	O
be	O
integrated	O
into	O
distributed	O
application	O
flows	O
.	O
</s>
<s>
CICS	B-Application
assets	O
can	O
be	O
accessed	O
from	O
remote	O
systems	O
,	O
and	O
can	O
access	O
remote	O
systems	O
;	O
user	O
identity	O
and	O
transactional	O
context	O
can	O
be	O
propagated	O
;	O
RESTful	B-Protocol
APIs	I-Protocol
can	O
be	O
composed	O
and	O
managed	O
;	O
devices	O
,	O
users	O
and	O
servers	O
can	O
interact	O
with	O
CICS	B-Application
using	O
standards-based	O
technologies	O
;	O
and	O
the	O
IBM	B-Language
WebSphere	I-Language
Liberty	O
environment	O
in	O
CICS	B-Application
promotes	O
the	O
rapid	O
adoption	O
of	O
new	O
technologies	O
.	O
</s>
<s>
The	O
initial	O
focus	O
was	O
the	O
IBM	B-Operating_System
XT/370	I-Operating_System
and	O
IBM	B-Operating_System
AT/370	I-Operating_System
.	O
</s>
<s>
Although	O
when	O
CICS	B-Application
is	O
mentioned	O
,	O
people	O
usually	O
mean	O
CICS	B-Application
Transaction	I-Application
Server	I-Application
,	O
the	O
CICS	B-Application
Family	O
refers	O
to	O
a	O
portfolio	O
of	O
transaction	B-General_Concept
servers	O
,	O
connectors	O
(	O
called	O
CICS	B-Application
Transaction	I-Application
Gateway	I-Application
)	O
and	O
CICS	B-Application
Tools	O
.	O
</s>
<s>
CICS	B-Application
on	O
distributed	O
platforms	O
—	O
not	O
mainframes	O
—	O
is	O
called	O
IBM	B-Application
TXSeries	I-Application
.	O
</s>
<s>
TXSeries	B-Application
is	O
distributed	O
transaction	B-General_Concept
processing	O
middleware	B-General_Concept
.	O
</s>
<s>
It	O
supports	O
C	O
,	O
C++	O
,	O
COBOL	B-Application
,	O
Java™	O
and	O
PL/I	B-Language
applications	O
in	O
cloud	O
environments	O
and	O
traditional	O
data	O
centers	O
.	O
</s>
<s>
TXSeries	B-Application
is	O
available	O
on	O
AIX	B-Application
,	O
Linux	O
x86	O
,	O
Windows	B-Application
,	O
Solaris	B-Application
,	O
and	O
HP-UX	B-Application
platforms	O
.	O
</s>
<s>
CICS	B-Application
is	O
also	O
available	O
on	O
other	O
operating	B-General_Concept
systems	I-General_Concept
,	O
notably	O
IBM	B-Application
i	I-Application
and	O
OS/2	B-Application
.	O
</s>
<s>
The	O
z/OS	B-Application
implementation	O
(	O
i.e.	O
,	O
CICS	B-Application
Transaction	I-Application
Server	I-Application
for	O
z/OS	B-Application
)	O
is	O
by	O
far	O
the	O
most	O
popular	O
and	O
significant	O
.	O
</s>
<s>
Two	O
versions	O
of	O
CICS	B-Application
were	O
previously	O
available	O
for	O
VM/CMS	B-Application
,	O
but	O
both	O
have	O
since	O
been	O
discontinued	O
.	O
</s>
<s>
In	O
1986	O
,	O
IBM	O
released	O
CICS/CMS	O
,	O
which	O
was	O
a	O
single-user	O
version	O
of	O
CICS	B-Application
designed	O
for	O
development	O
use	O
,	O
the	O
applications	O
later	O
being	O
transferred	O
to	O
an	O
MVS	B-Application
or	O
DOS/VS	B-Application
system	O
for	O
production	O
execution	O
.	O
</s>
<s>
Later	O
,	O
in	O
1988	O
,	O
IBM	O
released	O
CICS/VM	O
.	O
</s>
<s>
CICS/VM	O
was	O
intended	O
for	O
use	O
on	O
the	O
IBM	B-Device
9370	I-Device
,	O
a	O
low-end	O
mainframe	O
targeted	O
at	O
departmental	O
use	O
;	O
IBM	O
positioned	O
CICS/VM	O
running	O
on	O
departmental	O
or	O
branch	O
office	O
mainframes	O
for	O
use	O
in	O
conjunction	O
with	O
a	O
central	O
mainframe	O
running	O
CICS	B-Application
for	O
MVS	B-Application
.	O
</s>
<s>
Provisioning	O
,	O
management	O
and	O
analysis	O
of	O
CICS	B-Application
systems	O
and	O
applications	O
is	O
provided	O
by	O
CICS	B-Application
Tools	O
.	O
</s>
<s>
This	O
includes	O
performance	O
management	O
as	O
well	O
as	O
deployment	O
and	O
management	O
of	O
CICS	B-Application
resources	O
.	O
</s>
<s>
In	O
2015	O
,	O
the	O
four	O
core	O
foundational	O
CICS	B-Application
tools	O
(	O
and	O
the	O
CICS	B-Application
Optimization	O
Solution	O
Pack	O
for	O
z/OS	B-Application
)	O
were	O
updated	O
with	O
the	O
release	O
of	O
CICS	B-Application
Transaction	I-Application
Server	I-Application
for	O
z/OS	B-Application
5.3	O
.	O
</s>
<s>
The	O
four	O
core	O
CICS	B-Application
Tools	O
:	O
CICS	B-Application
Interdependency	O
Analyzer	O
for	O
z/OS	B-Application
,	O
CICS	B-Application
Deployment	O
Assistant	O
for	O
z/OS	B-Application
,	O
CICS	B-Application
Performance	O
Analyzer	O
for	O
z/OS	B-Application
and	O
CICS	B-Application
Configuration	O
Manager	O
for	O
z/OS	B-Application
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
for	O
z/OS	B-Application
has	O
used	O
the	O
following	O
release	O
numbers	O
:	O
</s>
<s>
Version	O
Announcement	O
Date	O
Release	O
Date	O
End	O
of	O
Service	O
Date	O
Features	O
2001-03-132001-03-30	O
Support	O
for	O
Spring	O
Boot	O
,	O
Jakarta	B-Language
EE	I-Language
8	I-Language
,	O
Node.js	B-Language
12	O
.	O
</s>
<s>
Support	O
for	O
Java	B-Language
11	O
,	O
Jakarta	O
EE	O
9.1	O
,	O
Eclipse	B-Application
MicroProfile	O
5	O
,	O
Node.js	B-Language
12	O
,	O
TLS	O
1.3	O
.	O
</s>
<s>
Multiple-user	O
interactive-transaction	O
application	O
programs	O
were	O
required	O
to	O
be	O
quasi-reentrant	O
in	O
order	O
to	O
support	O
multiple	O
concurrent	B-Operating_System
transaction	B-General_Concept
threads	B-Operating_System
.	O
</s>
<s>
The	O
modular	O
design	O
of	O
CICS	B-Application
reentrant	B-Operating_System
/	O
reusable	O
control	O
programs	O
meant	O
that	O
,	O
with	O
judicious	O
"	O
pruning	O
,	O
"	O
multiple	O
users	O
with	O
multiple	O
applications	O
could	O
be	O
executed	O
on	O
a	O
computer	O
with	O
just	O
32K	O
of	O
expensive	O
magnetic	O
core	O
physical	O
memory	B-General_Concept
(	O
including	O
the	O
operating	B-General_Concept
system	I-General_Concept
)	O
.	O
</s>
<s>
Considerable	O
effort	O
was	O
required	O
by	O
CICS	B-Application
application	O
programmers	O
to	O
make	O
their	O
transactions	O
as	O
efficient	O
as	O
possible	O
.	O
</s>
<s>
A	O
common	O
technique	O
was	O
to	O
limit	O
the	O
size	O
of	O
individual	O
programs	O
to	O
no	O
more	O
than	O
4,096	O
bytes	O
,	O
or	O
4K	O
,	O
so	O
that	O
CICS	B-Application
could	O
easily	O
reuse	O
the	O
memory	B-General_Concept
occupied	O
by	O
any	O
program	O
not	O
currently	O
in	O
use	O
for	O
another	O
program	O
or	O
other	O
application	O
storage	O
needs	O
.	O
</s>
<s>
When	O
virtual	B-Architecture
memory	I-Architecture
was	O
added	O
to	O
versions	O
OS/360	B-Application
in	O
1972	O
,	O
the	O
4K	O
strategy	O
became	O
even	O
more	O
important	O
to	O
reduce	O
paging	B-Architecture
and	O
thrashing	B-General_Concept
unproductive	O
resource-contention	O
overhead	O
.	O
</s>
<s>
The	O
efficiency	O
of	O
compiled	B-Language
high-level	O
COBOL	B-Application
and	O
PL/I	B-Language
language	O
programs	O
left	O
much	O
to	O
be	O
desired	O
.	O
</s>
<s>
Many	O
CICS	B-Application
application	O
programs	O
continued	O
to	O
be	O
written	O
in	O
assembler	O
language	O
,	O
even	O
after	O
COBOL	B-Application
and	O
PL/I	B-Language
support	O
became	O
available	O
.	O
</s>
<s>
With	O
1960s-and-1970s	O
hardware	B-Architecture
resources	O
expensive	O
and	O
scarce	O
,	O
a	O
competitive	O
"	O
game	O
"	O
developed	O
among	O
system	O
optimization	O
analysts	O
.	O
</s>
<s>
Each	O
person	O
had	O
to	O
either	O
(	O
a	O
)	O
reduce	O
the	O
number	O
of	O
bytes	O
of	O
code	O
required	O
,	O
or	O
(	O
b	O
)	O
reduce	O
the	O
number	O
of	O
CPU	B-Device
cycles	O
required	O
.	O
</s>
<s>
Small	O
shops	O
with	O
only	O
one	O
analyst	O
learned	O
CICS	B-Application
optimization	O
very	O
slowly	O
(	O
or	O
not	O
at	O
all	O
)	O
.	O
</s>
<s>
Because	O
application	O
programs	O
could	O
be	O
shared	O
by	O
many	O
concurrent	B-Operating_System
threads	B-Operating_System
,	O
the	O
use	O
of	O
static	B-General_Concept
variables	I-General_Concept
embedded	O
within	O
a	O
program	O
(	O
or	O
use	O
of	O
operating	B-General_Concept
system	I-General_Concept
memory	B-General_Concept
)	O
was	O
restricted	O
(	O
by	O
convention	O
only	O
)	O
.	O
</s>
<s>
Unfortunately	O
,	O
many	O
of	O
the	O
"	O
rules	O
"	O
were	O
frequently	O
broken	O
,	O
especially	O
by	O
COBOL	B-Application
programmers	O
who	O
might	O
not	O
understand	O
the	O
internals	O
of	O
their	O
programs	O
or	O
fail	O
to	O
use	O
the	O
necessary	O
restrictive	O
compile	B-Application
time	I-Application
options	O
.	O
</s>
<s>
This	O
resulted	O
in	O
"	O
non-re-entrant	O
"	O
code	O
that	O
was	O
often	O
unreliable	O
,	O
leading	O
to	O
spurious	O
storage	B-General_Concept
violations	I-General_Concept
and	O
entire	O
CICS	B-Application
system	O
crashes	O
.	O
</s>
<s>
Originally	O
,	O
the	O
entire	O
partition	O
,	O
or	O
Multiple	B-Application
Virtual	I-Application
Storage	I-Application
(	O
MVS	B-Application
)	O
region	O
,	O
operated	O
with	O
the	O
same	O
memory	B-General_Concept
protection	O
key	O
including	O
the	O
CICS	B-Application
kernel	B-Operating_System
code	O
.	O
</s>
<s>
Program	O
corruption	O
and	O
CICS	B-Application
control	O
block	O
corruption	O
was	O
a	O
frequent	O
cause	O
of	O
system	O
downtime	O
.	O
</s>
<s>
A	O
software	O
error	O
in	O
one	O
application	O
program	O
could	O
overwrite	O
the	O
memory	B-General_Concept
(	O
code	O
or	O
data	O
)	O
of	O
one	O
or	O
all	O
currently	O
running	O
application	O
transactions	O
.	O
</s>
<s>
These	O
shortcomings	O
persisted	O
for	O
multiple	O
new	O
releases	O
of	O
CICS	B-Application
over	O
a	O
period	O
of	O
more	O
than	O
20	O
years	O
,	O
in	O
spite	O
of	O
their	O
severity	O
and	O
the	O
fact	O
that	O
top-quality	O
CICS	B-Application
skills	O
were	O
in	O
high	O
demand	O
and	O
short	O
supply	O
.	O
</s>
<s>
They	O
were	O
addressed	O
in	O
TS	O
V3.3	O
,	O
V4.1	O
and	O
V5.2	O
with	O
the	O
Storage	O
Protection	O
,	O
Transaction	B-General_Concept
Isolation	O
and	O
Subspace	O
features	O
respectively	O
,	O
which	O
utilize	O
operating	B-General_Concept
system	I-General_Concept
hardware	B-Architecture
features	O
to	O
protect	O
the	O
application	O
code	O
and	O
the	O
data	O
within	O
the	O
same	O
address	O
space	O
even	O
though	O
the	O
applications	O
were	O
not	O
written	O
to	O
be	O
separated	O
.	O
</s>
<s>
CICS	B-Application
application	O
transactions	O
remain	O
mission-critical	O
for	O
many	O
public	O
utility	O
companies	O
,	O
large	O
banks	O
and	O
other	O
multibillion-dollar	O
financial	O
institutions	O
.	O
</s>
<s>
When	O
CICS	B-Application
was	O
first	O
released	O
,	O
it	O
only	O
supported	O
application	O
transaction	B-General_Concept
programs	O
written	O
in	O
IBM	B-Device
360	I-Device
Assembler	I-Device
.	O
</s>
<s>
COBOL	B-Application
and	O
PL/I	B-Language
support	O
were	O
added	O
years	O
later	O
.	O
</s>
<s>
Because	O
of	O
the	O
initial	O
assembler	O
orientation	O
,	O
requests	O
for	O
CICS	B-Application
services	O
were	O
made	O
using	O
assembler-language	O
macros	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
request	O
to	O
read	O
a	O
record	O
from	O
a	O
file	O
were	O
made	O
by	O
a	O
macro	O
call	O
to	O
the	O
"	O
File	O
Control	O
Program	O
"	O
of	O
CICS	B-Application
might	O
look	O
like	O
this	O
:	O
</s>
<s>
This	O
gave	O
rise	O
to	O
the	O
later	O
terminology	O
"	O
Macro-level	O
CICS.	O
"	O
</s>
<s>
When	O
high-level	B-Language
language	I-Language
support	O
was	O
added	O
,	O
the	O
macros	O
were	O
retained	O
and	O
the	O
code	O
was	O
converted	O
by	O
a	O
pre-compiler	O
that	O
expanded	O
the	O
macros	O
to	O
their	O
COBOL	B-Application
or	O
PL/I	B-Language
CALL	O
statement	O
equivalents	O
.	O
</s>
<s>
Thus	O
preparing	O
a	O
HLL	B-Language
application	O
was	O
effectively	O
a	O
"	O
two-stage	O
"	O
compile	B-Language
output	O
from	O
the	O
preprocessor	O
fed	O
into	O
the	O
HLL	B-Language
compiler	B-Language
as	O
input	O
.	O
</s>
<s>
COBOL	B-Application
considerations	O
:	O
unlike	O
PL/I	B-Language
,	O
IBM	O
COBOL	B-Application
does	O
not	O
normally	O
provide	O
for	O
the	O
manipulation	O
of	O
pointers	O
(	O
addresses	O
)	O
.	O
</s>
<s>
In	O
order	O
to	O
allow	O
COBOL	B-Application
programmers	O
to	O
access	O
CICS	B-Application
control	O
blocks	O
and	O
dynamic	O
storage	O
the	O
designers	O
resorted	O
to	O
what	O
was	O
essentially	O
a	O
hack	O
.	O
</s>
<s>
The	O
COBOL	B-Application
Linkage	O
Section	O
was	O
normally	O
used	O
for	O
inter-program	O
communication	O
,	O
such	O
as	O
parameter	O
passing	O
.	O
</s>
<s>
The	O
compiler	B-Language
generates	O
a	O
list	O
of	O
addresses	O
,	O
each	O
called	O
a	O
Base	O
Locator	O
for	O
Linkage	O
(	O
BLL	O
)	O
which	O
were	O
set	O
on	O
entry	O
to	O
the	O
called	O
program	O
.	O
</s>
<s>
CICS	B-Application
allows	O
the	O
programmer	O
to	O
access	O
and	O
manipulate	O
these	O
by	O
passing	O
the	O
address	O
of	O
the	O
list	O
as	O
the	O
first	O
argument	O
to	O
the	O
program	O
.	O
</s>
<s>
The	O
BLLs	O
can	O
then	O
be	O
dynamically	O
set	O
,	O
either	O
by	O
CICS	B-Application
or	O
by	O
the	O
application	O
to	O
allow	O
access	O
to	O
the	O
corresponding	O
structure	O
in	O
the	O
Linkage	O
Section	O
.	O
</s>
<s>
During	O
the	O
1980s	O
,	O
IBM	O
at	O
Hursley	O
Park	O
produced	O
a	O
version	O
of	O
CICS	B-Application
that	O
supported	O
what	O
became	O
known	O
as	O
"	O
Command-level	O
CICS	B-Application
"	O
which	O
still	O
supported	O
the	O
older	O
programs	O
but	O
introduced	O
a	O
new	O
API	O
style	O
to	O
application	O
programs	O
.	O
</s>
<s>
This	O
is	O
pre-processed	O
by	O
a	O
pre-compile	O
batch	O
translation	O
stage	O
,	O
which	O
converts	O
the	O
embedded	O
commands	O
(	O
EXECs	O
)	O
into	O
call	O
statements	O
to	O
a	O
stub	O
subroutine	O
.	O
</s>
<s>
Initially	O
,	O
at	O
execution	O
time	O
,	O
the	O
command-level	O
commands	O
were	O
converted	O
using	O
a	O
run-time	O
translator	O
,	O
"	O
The	O
EXEC	O
Interface	O
Program	O
"	O
,	O
to	O
the	O
old	O
Macro-level	O
call	O
,	O
which	O
was	O
then	O
executed	O
by	O
the	O
mostly	O
unchanged	O
CICS	B-Application
nucleus	B-Operating_System
programs	O
.	O
</s>
<s>
But	O
when	O
the	O
CICS	B-Application
Kernel	B-Operating_System
was	O
re-written	O
for	O
TS	O
V3	O
,	O
EXEC	O
CICS	B-Application
became	O
the	O
only	O
way	O
to	O
program	O
CICS	B-Application
applications	O
,	O
as	O
many	O
of	O
the	O
underlying	O
interfaces	O
had	O
changed	O
.	O
</s>
<s>
The	O
Command-level-only	O
CICS	B-Application
introduced	O
in	O
the	O
early	O
1990s	O
offered	O
some	O
advantages	O
over	O
earlier	O
versions	O
of	O
CICS	B-Application
.	O
</s>
<s>
There	O
were	O
a	O
significant	O
number	O
of	O
users	O
who	O
ran	O
CICS	B-Application
V2	O
application-owning	O
regions	O
(	O
AORs	O
)	O
to	O
continue	O
to	O
run	O
macro	O
code	O
for	O
many	O
years	O
after	O
the	O
change	O
to	O
V3	O
.	O
</s>
<s>
It	O
was	O
also	O
possible	O
to	O
execute	O
old	O
Macro-level	O
programs	O
using	O
conversion	O
software	O
such	O
as	O
APT	O
International	O
's	O
Command	B-Application
CICS	I-Application
.	O
</s>
<s>
Recent	O
CICS	B-Application
Transaction	I-Application
Server	I-Application
enhancements	O
include	O
support	O
for	O
a	O
number	O
of	O
modern	O
programming	O
styles	O
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
Version	O
5.6	O
introduced	O
enhanced	O
support	O
for	O
Java	B-Language
to	O
deliver	O
a	O
cloud-native	O
experience	O
for	O
Java	B-Language
developers	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
new	O
CICS	B-Application
Java	B-Language
API	O
(	O
)	O
allows	O
easier	O
unit	O
testing	O
using	O
mocking	O
and	O
stubbing	O
approaches	O
,	O
and	O
can	O
be	O
run	O
remotely	O
on	O
the	O
developer	O
’s	O
local	O
workstation	O
.	O
</s>
<s>
A	O
set	O
of	O
enable	O
developers	O
to	O
resolve	O
Java	B-Language
dependencies	O
using	O
popular	O
dependency	O
management	O
tools	O
such	O
as	O
Apache	B-Language
Maven	I-Language
and	O
Gradle	B-Language
.	O
</s>
<s>
Plug-ins	O
for	O
Maven	B-Language
(	O
)	O
and	O
Gradle	B-Language
(	O
)	O
are	O
also	O
provided	O
to	O
simplify	O
automated	O
building	O
of	O
CICS	B-Application
bundles	O
,	O
using	O
familiar	O
IDEs	O
like	O
Eclipse	B-Application
,	O
IntelliJ	B-Language
IDEA	I-Language
,	O
and	O
Visual	B-Language
Studio	I-Language
Code	I-Language
.	O
</s>
<s>
In	O
addition	O
,	O
Node.js	B-Language
z/OS	B-Application
support	O
is	O
enhanced	O
for	O
version	O
12	O
,	O
providing	O
faster	O
startup	O
,	O
better	O
default	O
heap	O
limits	O
,	O
updates	O
to	O
the	O
V8	O
JavaScript	O
engine	O
,	O
etc	O
.	O
</s>
<s>
Support	O
for	O
Jakarta	B-Language
EE	I-Language
8	I-Language
is	O
also	O
included	O
.	O
</s>
<s>
CICS	B-Application
TS	O
5.5	O
introduced	O
support	O
for	O
IBM	O
SDK	O
for	O
Node.js	B-Language
,	O
providing	O
a	O
full	O
JavaScript	O
runtime	O
,	O
server-side	O
APIs	O
,	O
and	O
libraries	O
to	O
efficiently	O
build	O
high-performance	O
,	O
highly	O
scalable	O
network	O
applications	O
for	O
IBM	B-Device
Z	I-Device
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
Version	O
2.1	O
introduced	O
support	O
for	O
Java	B-Language
.	O
</s>
<s>
CICS	B-Application
Transaction	I-Application
Server	I-Application
Version	O
2.2	O
supported	O
the	O
Software	O
Developers	O
Toolkit	O
.	O
</s>
<s>
CICS	B-Application
provides	O
the	O
same	O
run-time	O
container	O
as	O
IBM	O
's	O
WebSphere	B-Language
product	O
family	O
so	O
Java	B-Language
EE	I-Language
applications	O
are	O
portable	O
between	O
CICS	B-Application
and	O
Websphere	B-Language
and	O
there	O
is	O
common	O
tooling	O
for	O
the	O
development	O
and	O
deployment	O
of	O
Java	B-Language
EE	I-Language
applications	O
.	O
</s>
<s>
In	O
addition	O
,	O
CICS	B-Application
placed	O
an	O
emphasis	O
on	O
"	O
wrapping	O
"	O
existing	O
application	O
programs	O
inside	O
modern	O
interfaces	O
so	O
that	O
long-established	O
business	O
functions	O
can	O
be	O
incorporated	O
into	O
more	O
modern	O
services	O
.	O
</s>
<s>
These	O
include	O
WSDL	O
,	O
SOAP	B-Application
and	O
JSON	B-General_Concept
interfaces	O
that	O
wrap	O
legacy	O
code	O
so	O
that	O
a	O
web	O
or	O
mobile	O
application	O
can	O
obtain	O
and	O
update	O
the	O
core	O
business	O
objects	O
without	O
requiring	O
a	O
major	O
rewrite	O
of	O
the	O
back-end	O
functions	O
.	O
</s>
<s>
A	O
CICS	B-Application
transaction	B-General_Concept
is	O
a	O
set	O
of	O
operations	O
that	O
perform	O
a	O
task	B-General_Concept
together	O
.	O
</s>
<s>
A	O
primary	O
characteristic	O
of	O
a	O
transaction	B-General_Concept
is	O
that	O
it	O
should	O
be	O
atomic	B-General_Concept
.	O
</s>
<s>
On	O
IBM	B-Device
Z	I-Device
servers	O
,	O
CICS	B-Application
easily	O
supports	O
thousands	O
of	O
transactions	O
per	O
second	O
,	O
making	O
it	O
a	O
mainstay	O
of	O
enterprise	O
computing	O
.	O
</s>
<s>
CICS	B-Application
applications	O
comprise	O
transactions	O
,	O
which	O
can	O
be	O
written	O
in	O
numerous	O
programming	O
languages	O
,	O
including	O
COBOL	B-Application
,	O
PL/I	B-Language
,	O
C	O
,	O
C++	O
,	O
IBM	B-Device
Basic	I-Device
Assembly	I-Device
Language	I-Device
,	O
Rexx	B-Language
,	O
and	O
Java	B-Language
.	O
</s>
<s>
Each	O
CICS	B-Application
program	O
is	O
initiated	O
using	O
a	O
transaction	B-General_Concept
identifier	O
.	O
</s>
<s>
CICS	B-Application
screens	O
are	O
usually	O
sent	O
as	O
a	O
construct	O
called	O
a	O
map	O
,	O
a	O
module	O
created	O
with	O
Basic	O
Mapping	O
Support	O
(	O
BMS	O
)	O
assembler	O
macros	O
or	O
third-party	O
tools	O
.	O
</s>
<s>
CICS	B-Application
screens	O
may	O
contain	O
text	O
that	O
is	O
highlighted	O
,	O
has	O
different	O
colors	O
,	O
and/or	O
blinks	O
depending	O
on	O
the	O
terminal	O
type	O
used	O
.	O
</s>
<s>
An	O
example	O
of	O
how	O
a	O
map	O
can	O
be	O
sent	O
through	O
COBOL	B-Application
is	O
given	O
below	O
.	O
</s>
<s>
The	O
end	O
user	O
inputs	O
data	O
,	O
which	O
is	O
made	O
accessible	O
to	O
the	O
program	O
by	O
receiving	O
a	O
map	O
from	O
CICS	B-Application
.	O
</s>
<s>
This	O
was	O
assembled	O
to	O
generate	O
both	O
the	O
physical	O
map	O
set	O
a	O
load	O
module	O
in	O
a	O
CICS	B-Application
load	O
library	O
and	O
a	O
symbolic	O
map	O
set	O
a	O
structure	O
definition	O
or	O
DSECT	O
in	O
PL/I	B-Language
,	O
COBOL	B-Application
,	O
assembler	O
,	O
etc	O
.	O
</s>
<s>
In	O
the	O
z/OS	B-Application
environment	O
,	O
a	O
CICS	B-Application
installation	O
comprises	O
one	O
or	O
more	O
"	O
regions	O
"	O
(	O
generally	O
referred	O
to	O
as	O
a	O
"	O
CICS	B-Application
Region	O
"	O
)	O
,	O
spread	O
across	O
one	O
or	O
more	O
z/OS	B-Application
system	O
images	O
.	O
</s>
<s>
Although	O
it	O
processes	O
interactive	O
transactions	O
,	O
each	O
CICS	B-Application
region	O
is	O
usually	O
started	O
as	O
a	O
batch	O
processing|batch	O
address	O
space	O
with	O
standard	O
JCL	B-Application
statements	O
:	O
it	O
's	O
a	O
job	O
that	O
runs	O
indefinitely	O
until	O
shutdown	O
.	O
</s>
<s>
Alternatively	O
,	O
each	O
CICS	B-Application
region	O
may	O
be	O
started	O
as	O
a	O
started	B-Operating_System
task	I-Operating_System
.	O
</s>
<s>
Whether	O
a	O
batch	B-General_Concept
job	I-General_Concept
or	O
a	O
started	B-Operating_System
task	I-Operating_System
,	O
CICS	B-Application
regions	O
may	O
run	O
for	O
days	O
,	O
weeks	O
,	O
or	O
even	O
months	O
before	O
shutting	O
down	O
for	O
maintenance	O
(	O
MVS	B-Application
or	O
CICS	B-Application
)	O
.	O
</s>
<s>
Cold	O
starts	O
of	O
large	O
CICS	B-Application
regions	O
with	O
many	O
resources	O
can	O
take	O
a	O
long	O
time	O
as	O
all	O
the	O
definitions	O
are	O
re-processed	O
.	O
</s>
<s>
avoiding	O
the	O
workload	O
capacity	O
limitations	O
of	O
a	O
single	O
region	O
,	O
or	O
address	O
space	O
,	O
or	O
mainframe	O
instance	O
in	O
the	O
case	O
of	O
a	O
z/OS	B-Application
SysPlex	B-Operating_System
.	O
</s>
<s>
But	O
not	O
all	O
CICS	B-Application
applications	O
use	O
VSAM	O
as	O
the	O
primary	O
data	O
source	O
(	O
or	O
historically	O
other	O
single	O
address	O
space	O
at	O
a	O
time	O
datastores	O
such	O
as	O
CA	O
Datacom	O
)	O
-	O
many	O
use	O
either	O
IMS/DB	B-Application
or	O
Db2	B-Application
as	O
the	O
database	O
,	O
and/or	O
MQ	B-Application
as	O
a	O
queue	O
manager	O
.	O
</s>
<s>
For	O
all	O
these	O
cases	O
,	O
TORs	O
can	O
load-balance	O
transactions	O
to	O
sets	O
of	O
AORs	O
which	O
then	O
directly	O
use	O
the	O
shared	O
databases/queues	O
.	O
</s>
<s>
CICS	B-Application
supports	O
XA	O
two-phase	O
commit	O
between	O
data	O
stores	O
and	O
so	O
transactions	O
that	O
spanned	O
MQ	B-Application
,	O
VSAM/RLS	O
and	O
Db2	B-Application
,	O
for	O
example	O
,	O
are	O
possible	O
with	O
ACID	O
properties	O
.	O
</s>
<s>
CICS	B-Application
supports	O
distributed	O
transactions	O
using	O
SNA	O
LU6.2	O
protocol	O
between	O
the	O
address	O
spaces	O
which	O
can	O
be	O
running	O
on	O
the	O
same	O
or	O
different	O
clusters	O
.	O
</s>
<s>
In	O
practice	O
there	O
are	O
issues	O
with	O
this	O
if	O
a	O
system	O
or	O
communications	O
failure	O
occurs	O
because	O
the	O
transaction	B-General_Concept
disposition	O
(	O
backout	O
or	O
commit	O
)	O
may	O
be	O
in-doubt	O
if	O
one	O
of	O
the	O
communicating	O
nodes	O
has	O
not	O
recovered	O
.	O
</s>
<s>
At	O
the	O
time	O
of	O
CICS	B-Application
ESA	O
V3.2	O
,	O
in	O
the	O
early	O
1990s	O
,	O
IBM	O
faced	O
the	O
challenge	O
of	O
how	O
to	O
get	O
CICS	B-Application
to	O
exploit	O
the	O
new	O
zOS	B-Application
Sysplex	B-Operating_System
mainframe	O
line	O
.	O
</s>
<s>
The	O
Sysplex	B-Operating_System
was	O
to	O
be	O
based	O
on	O
CMOS	B-Device
(	O
Complementary	O
Metal	O
Oxide	O
Silicon	O
)	O
rather	O
than	O
the	O
existing	O
ECL	B-General_Concept
(	O
Emitter	B-General_Concept
Coupled	I-General_Concept
Logic	I-General_Concept
)	O
hardware	B-Architecture
.	O
</s>
<s>
The	O
cost	O
of	O
scaling	O
the	O
mainframe-unique	O
ECL	B-General_Concept
was	O
much	O
higher	O
than	O
CMOS	B-Device
which	O
was	O
being	O
developed	O
by	O
a	O
keiretsu	O
with	O
high-volume	O
use	O
cases	O
such	O
as	O
Sony	O
PlayStation	O
to	O
reduce	O
the	O
unit	O
cost	O
of	O
each	O
generation	O
's	O
CPUs	B-Device
.	O
</s>
<s>
The	O
ECL	B-General_Concept
was	O
also	O
expensive	O
for	O
users	O
to	O
run	O
because	O
the	O
gate	O
drain	O
current	O
produced	O
so	O
much	O
heat	O
that	O
the	O
CPU	B-Device
had	O
to	O
packaged	O
into	O
a	O
special	O
module	O
called	O
a	O
Thermal	O
Conduction	O
Module	O
(	O
TCM	O
)	O
that	O
had	O
inert	O
gas	O
pistons	O
and	O
needed	O
plumbed	O
to	O
be	O
high-volume	O
chilled	O
water	O
to	O
be	O
cooled	O
.	O
</s>
<s>
But	O
the	O
air-cooled	O
CMOS	B-Device
technology	O
's	O
CPU	B-Device
speed	O
initially	O
was	O
much	O
slower	O
than	O
the	O
ECL	B-General_Concept
(	O
notably	O
the	O
boxes	O
available	O
from	O
the	O
mainframe-clone	O
makers	O
Amdahl	O
and	O
Hitachi	O
)	O
.	O
</s>
<s>
This	O
was	O
especially	O
concerning	O
to	O
IBM	O
in	O
the	O
CICS	B-Application
context	O
as	O
almost	O
all	O
the	O
largest	O
mainframe	O
customers	O
were	O
running	O
CICS	B-Application
and	O
for	O
many	O
of	O
them	O
it	O
was	O
the	O
primary	O
mainframe	O
workload	O
.	O
</s>
<s>
To	O
achieve	O
the	O
same	O
total	O
transaction	B-General_Concept
throughput	O
on	O
a	O
Sysplex	B-Operating_System
multiple	O
boxes	O
would	O
need	O
to	O
be	O
used	O
in	O
parallel	O
for	O
each	O
workload	O
but	O
a	O
CICS	B-Application
address	O
space	O
,	O
due	O
to	O
its	O
semi-reentrant	O
application	O
programming	O
model	O
,	O
could	O
not	O
exploit	O
more	O
than	O
about	O
1.5	O
processors	O
on	O
one	O
box	O
at	O
the	O
time	O
even	O
with	O
use	O
of	O
MVS	B-Application
sub-tasks	O
.	O
</s>
<s>
Without	O
this	O
,	O
these	O
customers	O
would	O
tend	O
to	O
move	O
to	O
the	O
competitors	O
rather	O
than	O
Sysplex	B-Operating_System
as	O
they	O
scaled	O
up	O
the	O
CICS	B-Application
workloads	O
.	O
</s>
<s>
There	O
was	O
considerable	O
debate	O
inside	O
IBM	O
as	O
to	O
whether	O
the	O
right	O
approach	O
would	O
be	O
to	O
break	O
upward	O
compatibility	O
for	O
applications	O
and	O
move	O
to	O
a	O
model	O
like	O
IMS/DC	O
which	O
was	O
fully	O
reentrant	B-Operating_System
,	O
or	O
to	O
extend	O
the	O
approach	O
customers	O
had	O
adopted	O
to	O
more	O
fully	O
exploit	O
a	O
single	O
mainframe	O
's	O
power	O
using	O
multi-region	O
operation	O
(	O
MRO	O
)	O
.	O
</s>
<s>
Eventually	O
the	O
second	O
path	O
was	O
adopted	O
after	O
the	O
CICS	B-Application
user	O
community	O
was	O
consulted	O
and	O
vehemently	O
opposed	O
breaking	O
upward	O
compatibility	O
given	O
that	O
they	O
had	O
the	O
prospect	O
of	O
Y2K	O
to	O
contend	O
with	O
at	O
that	O
time	O
and	O
did	O
not	O
see	O
the	O
value	O
in	O
re-writing	O
and	O
testing	O
millions	O
of	O
lines	O
of	O
mainly	O
COBOL	B-Application
,	O
PL/1	B-Language
,	O
or	O
assembler	O
code	O
.	O
</s>
<s>
The	O
IBM	O
recommended	O
structure	O
for	O
CICS	B-Application
on	O
Sysplex	B-Operating_System
was	O
that	O
at	O
least	O
one	O
CICS	B-Application
Terminal	O
Owning	O
Region	O
was	O
placed	O
on	O
each	O
Sysplex	B-Operating_System
node	O
which	O
dispatched	O
transactions	O
to	O
many	O
Application	O
Owning	O
Regions	O
(	O
AORs	O
)	O
spread	O
across	O
the	O
entire	O
Sysplex	B-Operating_System
.	O
</s>
<s>
If	O
these	O
applications	O
needed	O
to	O
access	O
shared	O
resources	O
they	O
either	O
used	O
a	O
Sysplex-exploiting	O
datastore	O
(	O
such	O
as	O
IBM	B-Application
Db2	I-Application
or	O
IMS/DB	B-Application
)	O
or	O
concentrated	O
,	O
by	O
function-shipping	O
,	O
the	O
resource	O
requests	O
into	O
singular-per-resource	O
Resource	O
Owing	O
Regions	O
(	O
RORs	O
)	O
including	O
File	O
Owning	O
Regions	O
(	O
FORs	O
)	O
for	O
VSAM	O
and	O
CICS	B-Application
Data	O
Tables	O
,	O
Queue	O
Owning	O
Regions	O
(	O
QORs	O
)	O
for	O
MQ	B-Application
,	O
CICS	B-Application
Transient	O
Data	O
(	O
TD	O
)	O
and	O
CICS	B-Application
Temporary	O
Storage	O
(	O
TS	O
)	O
.	O
</s>
<s>
This	O
preserved	O
compatibility	O
for	O
legacy	O
applications	O
at	O
the	O
expense	O
of	O
operational	O
complexity	O
to	O
configure	O
and	O
manage	O
many	O
CICS	B-Application
regions	O
.	O
</s>
<s>
In	O
subsequent	O
releases	O
and	O
versions	O
,	O
CICS	B-Application
was	O
able	O
to	O
exploit	O
new	O
Sysplex-exploiting	O
facilities	O
in	O
VSAM/RLS	O
,	O
MQ	B-Application
for	O
zOS	B-Application
and	O
placed	O
its	O
own	O
Data	O
Tables	O
,	O
TD	O
,	O
and	O
TS	O
resources	O
into	O
the	O
architected	O
shared	O
resource	O
manager	O
for	O
the	O
Sysplex	B-Operating_System
->	O
the	O
Coupling	B-Device
Facility	I-Device
or	O
CF	O
,	O
dispensing	O
with	O
the	O
need	O
for	O
most	O
RORs	O
.	O
</s>
<s>
The	O
CF	O
provides	O
a	O
mapped	O
view	O
of	O
resources	O
including	O
a	O
shared	O
timebase	O
,	O
buffer	O
pools	O
,	O
locks	O
and	O
counters	O
with	O
hardware	B-Architecture
messaging	O
assists	O
that	O
made	O
sharing	O
resources	O
across	O
the	O
Sysplex	B-Operating_System
both	O
more	O
efficient	O
than	O
polling	O
and	O
reliable	O
(	O
utilizing	O
a	O
semi-synchronized	O
backup	O
CF	O
for	O
use	O
in	O
case	O
of	O
failure	O
)	O
.	O
</s>
<s>
By	O
this	O
time	O
,	O
the	O
CMOS	B-Device
line	O
had	O
individual	O
boxes	O
that	O
exceeded	O
the	O
power	O
available	O
by	O
the	O
fastest	O
ECL	B-General_Concept
box	O
with	O
more	O
processors	O
per	O
CPU	B-Device
and	O
when	O
these	O
were	O
coupled	O
together	O
32	O
or	O
more	O
nodes	O
would	O
be	O
able	O
to	O
scale	O
two	O
orders	O
of	O
magnitude	O
larger	O
in	O
total	O
power	O
for	O
a	O
single	O
workload	O
.	O
</s>
<s>
For	O
example	O
,	O
by	O
2002	O
,	O
Charles	O
Schwab	O
was	O
running	O
a	O
"	O
MetroPlex	O
"	O
consisting	O
of	O
a	O
redundant	O
pair	O
of	O
its	O
mainframe	O
Sysplexes	O
in	O
two	O
locations	O
in	O
Phoenix	O
,	O
AZ	O
each	O
with	O
32	O
nodes	O
driven	O
by	O
one	O
shared	O
CICS/DB/2	O
workload	O
to	O
support	O
the	O
vast	O
volume	O
of	O
pre-dotcom-bubble	O
web	O
client	O
inquiry	O
requests	O
.	O
</s>
<s>
This	O
cheaper	O
,	O
much	O
more	O
scalable	O
CMOS	B-Device
technology	O
base	O
,	O
and	O
the	O
huge	O
investment	O
costs	O
of	O
having	O
to	O
both	O
get	O
to	O
64bit	O
addressing	O
and	O
independently	O
produce	O
cloned	O
CF	O
functionality	O
drove	O
the	O
IBM-mainframe	O
clone	O
makers	O
out	O
of	O
the	O
business	O
one	O
by	O
one	O
.	O
</s>
<s>
The	O
objective	O
of	O
recovery/restart	O
in	O
CICS	B-Application
is	O
to	O
minimize	O
and	O
if	O
possible	O
eliminate	O
damage	O
done	O
to	O
Online	O
System	O
when	O
a	O
failure	O
occurs	O
,	O
so	O
that	O
system	O
and	O
data	O
integrity	O
is	O
maintained	O
.	O
</s>
<s>
If	O
the	O
CICS	B-Application
region	O
was	O
shutdown	O
instead	O
of	O
failing	O
it	O
will	O
perform	O
a	O
"	O
Warm	O
"	O
start	O
exploiting	O
the	O
checkpoint	O
written	O
at	O
shutdown	O
.	O
</s>
<s>
The	O
CICS	B-Application
region	O
can	O
also	O
be	O
forced	O
to	O
"	O
Cold	O
"	O
start	O
which	O
reloads	O
all	O
definitions	O
and	O
wipes	O
out	O
the	O
log	O
,	O
leaving	O
the	O
resources	O
in	O
whatever	O
state	O
they	O
are	O
in	O
.	O
</s>
<s>
Under	O
CICS	B-Application
,	O
following	O
are	O
some	O
of	O
the	O
resources	O
which	O
are	O
considered	O
recoverable	O
.	O
</s>
<s>
If	O
one	O
wishes	O
these	O
resources	O
to	O
be	O
recoverable	O
then	O
special	O
options	O
must	O
be	O
specified	O
in	O
relevant	O
CICS	B-Application
definitions	O
:	O
</s>
<s>
CICS	B-Application
also	O
offers	O
extensive	O
recovery/restart	O
facilities	O
for	O
users	O
to	O
establish	O
their	O
own	O
recovery/restart	O
capability	O
in	O
their	O
CICS	B-Application
system	O
.	O
</s>
<s>
Each	O
CICS	B-Application
region	O
comprises	O
one	O
major	O
task	B-General_Concept
on	O
which	O
every	O
transaction	B-General_Concept
runs	O
,	O
although	O
certain	O
services	O
such	O
as	O
access	O
to	O
IBM	B-Application
Db2	I-Application
data	O
use	O
other	O
tasks	O
(	O
TCBs	O
)	O
.	O
</s>
<s>
Within	O
a	O
region	O
,	O
transactions	O
are	O
cooperatively	B-Operating_System
multitasked	I-Operating_System
they	O
are	O
expected	O
to	O
be	O
well-behaved	O
and	O
yield	O
the	O
CPU	B-Device
rather	O
than	O
wait	O
.	O
</s>
<s>
CICS	B-Application
services	O
handle	O
this	O
automatically	O
.	O
</s>
<s>
Each	O
unique	O
CICS	B-Application
"	O
Task	B-General_Concept
"	O
or	O
transaction	B-General_Concept
is	O
allocated	O
its	O
own	O
dynamic	O
memory	B-General_Concept
at	O
start-up	O
and	O
subsequent	O
requests	O
for	O
additional	O
memory	B-General_Concept
were	O
handled	O
by	O
a	O
call	O
to	O
the	O
"	O
Storage	O
Control	O
program	O
"	O
(	O
part	O
of	O
the	O
CICS	B-Application
nucleus	B-Operating_System
or	O
"	O
kernel	B-Operating_System
"	O
)	O
,	O
which	O
is	O
analogous	O
to	O
an	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
A	O
CICS	B-Application
system	O
consists	O
of	O
the	O
online	O
nucleus	B-Operating_System
,	O
batch	O
support	O
programs	O
,	O
and	O
applications	O
services	O
.	O
</s>
<s>
The	O
original	O
CICS	B-Application
nucleus	B-Operating_System
consisted	O
of	O
a	O
number	O
of	O
functional	O
modules	O
written	O
in	O
370	O
assembler	O
until	O
V3	O
:	O
</s>
<s>
Starting	O
in	O
V3	O
,	O
the	O
CICS	B-Application
nucleus	B-Operating_System
was	O
rewritten	O
into	O
a	O
kernel-and-domain	O
structure	O
using	O
IBM	O
's	O
PL/AS	B-Language
language	O
which	O
is	O
compiled	B-Language
into	O
assembler	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
operated	O
as	O
a	O
switcher	O
for	O
inter-domain	O
requests	O
initially	O
this	O
proved	O
expensive	O
for	O
frequently	O
called	O
domains	O
(	O
such	O
as	O
Trace	O
)	O
but	O
by	O
utilizing	O
PL/AS	B-Language
macros	O
these	O
calls	O
were	O
in-lined	O
without	O
compromising	O
on	O
the	O
separate	O
domain	O
design	O
.	O
</s>
<s>
In	O
later	O
versions	O
,	O
completely	O
redesigned	O
domains	O
were	O
added	O
like	O
the	O
Logging	O
Domain	O
DFHLG	O
and	O
Transaction	B-General_Concept
Domain	O
DFHTM	O
that	O
replaced	O
the	O
Journal	O
Control	O
Program	O
(	O
JCP	O
)	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
online	O
functions	O
CICS	B-Application
has	O
several	O
support	O
programs	O
that	O
run	O
as	O
batch	B-General_Concept
jobs	I-General_Concept
.	O
</s>
<s>
The	O
following	O
components	O
of	O
CICS	B-Application
support	O
application	O
development	O
.	O
</s>
