<s>
Transaction	B-Operating_System
Processing	I-Operating_System
Facility	I-Operating_System
(	O
TPF	O
)	O
is	O
an	O
IBM	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
for	O
mainframe	B-Device
computers	O
descended	O
from	O
the	O
IBM	B-Application
System/360	I-Application
family	O
,	O
including	O
zSeries	B-Device
and	O
System	B-Device
z9	I-Device
.	O
</s>
<s>
While	O
there	O
are	O
other	O
industrial-strength	O
transaction	B-Application
processing	I-Application
systems	I-Application
,	O
notably	O
IBM	O
's	O
own	O
CICS	B-Application
and	O
IMS	B-Application
,	O
TPF	O
's	O
specialty	O
is	O
extreme	O
volume	O
,	O
large	O
numbers	O
of	O
concurrent	O
users	O
,	O
and	O
very	O
fast	O
response	O
times	O
.	O
</s>
<s>
The	O
TPF	O
passenger	O
reservation	O
application	O
PARS	B-Application
,	O
or	O
its	O
international	O
version	O
IPARS	O
,	O
is	O
used	O
by	O
many	O
airlines	O
.	O
</s>
<s>
PARS	B-Application
is	O
an	O
application	O
program	O
;	O
TPF	O
is	O
an	O
operating	O
system	O
.	O
</s>
<s>
A	O
close	O
cousin	O
of	O
TPF	O
,	O
the	O
transaction	O
monitor	O
ALCS	B-Application
,	O
was	O
developed	O
by	O
IBM	O
to	O
integrate	O
TPF	O
services	O
into	O
the	O
more	O
common	O
mainframe	B-Device
operating	O
system	O
MVS	B-Application
,	O
now	O
z/OS	B-Application
.	O
</s>
<s>
TPF	O
evolved	O
from	O
the	O
Airlines	B-Application
Control	I-Application
Program	I-Application
(	O
ACP	O
)	O
,	O
a	O
free	O
package	O
developed	O
in	O
the	O
mid-1960s	O
by	O
IBM	O
in	O
association	O
with	O
major	O
North	O
American	O
and	O
European	O
airlines	O
.	O
</s>
<s>
TPF	O
was	O
traditionally	O
an	O
IBM	B-Device
System/370	I-Device
assembly	B-Language
language	I-Language
environment	O
for	O
performance	O
reasons	O
,	O
and	O
many	O
TPF	O
assembler	B-Language
applications	O
persist	O
.	O
</s>
<s>
However	O
,	O
more	O
recent	O
versions	O
of	O
TPF	O
encourage	O
the	O
use	O
of	O
C	B-Language
.	O
Another	O
programming	O
language	O
called	O
SabreTalk	B-Language
was	O
born	O
and	O
died	O
on	O
TPF	O
.	O
</s>
<s>
IBM	O
announced	O
the	O
delivery	O
of	O
the	O
current	O
release	O
of	O
TPF	O
,	O
dubbed	O
z/TPF	B-Operating_System
V1.1	O
,	O
in	O
September	O
2005	O
.	O
</s>
<s>
Most	O
significantly	O
,	O
z/TPF	B-Operating_System
adds	O
64-bit	O
addressing	O
and	O
mandates	O
use	O
of	O
the	O
64-bit	O
GNU	B-Operating_System
development	O
tools	O
.	O
</s>
<s>
The	O
GCC	B-Application
compiler	I-Application
and	O
the	O
DIGNUS	O
Systems/C	O
++	O
and	O
Systems/C	O
are	O
the	O
only	O
supported	O
compilers	O
for	O
z/TPF	B-Operating_System
.	O
</s>
<s>
The	O
Dignus	O
compilers	O
offer	O
reduced	O
source	O
code	O
changes	O
when	O
moving	O
from	O
TPF	O
4.1	O
to	O
z/TPF	B-Operating_System
.	O
</s>
<s>
Current	O
users	O
include	O
Sabre	B-Application
(	O
reservations	O
)	O
,	O
VISA	O
Inc	O
.	O
(	O
authorizations	O
)	O
,	O
American	O
Airlines	O
,	O
American	O
Express	O
(	O
authorizations	O
)	O
,	O
DXC	O
Technology	O
SHARES	O
(	O
reservations	O
)	O
,	O
Amtrak	O
,	O
Marriott	O
International	O
,	O
Travelport	O
(	O
Galileo	O
,	O
Apollo	O
,	O
Worldspan	O
)	O
,	O
Citibank	O
,	O
Trenitalia	O
(	O
reservations	O
)	O
,	O
Delta	O
Air	O
Lines	O
(	O
reservations	O
and	O
operations	O
)	O
and	O
Japan	O
Airlines	O
.	O
</s>
<s>
Although	O
IBM	O
's	O
3083	O
was	O
aimed	O
at	O
running	O
TPF	O
on	O
a	O
"	O
fast	O
...	O
uniprocessor	B-Operating_System
,	O
"	O
,	O
TPF	O
is	O
capable	O
of	O
running	O
on	O
a	O
multiprocessor	B-Operating_System
,	O
that	O
is	O
,	O
on	O
systems	O
in	O
which	O
there	O
is	O
more	O
than	O
one	O
CPU	O
.	O
</s>
<s>
Within	O
the	O
LPAR	B-Device
,	O
the	O
CPUs	O
are	O
referred	O
to	O
as	O
instruction	O
streams	O
or	O
simply	O
I-streams	O
.	O
</s>
<s>
When	O
running	O
on	O
a	O
LPAR	B-Device
with	O
more	O
than	O
one	O
I-stream	O
,	O
TPF	O
is	O
said	O
to	O
be	O
running	O
tightly	O
coupled	O
.	O
</s>
<s>
TPF	O
adheres	O
to	O
SMP	B-Operating_System
concepts	O
;	O
no	O
concept	O
of	O
NUMA-based	O
distinctions	O
between	O
memory	O
addresses	O
exist	O
.	O
</s>
<s>
In	O
cases	O
where	O
loosely	B-Application
coupled	I-Application
configurations	O
are	O
populated	O
by	O
multiprocessor	B-Operating_System
CPCs	O
(	O
Central	O
Processing	O
Complex	O
,	O
i.e.	O
</s>
<s>
the	O
physical	O
machine	O
packaged	O
in	O
one	O
system	O
cabinet	O
)	O
,	O
SMP	B-Operating_System
takes	O
place	O
within	O
the	O
CPC	O
as	O
described	O
here	O
,	O
whereas	O
sharing	O
of	O
inter-CPC	O
resources	O
takes	O
place	O
as	O
described	O
under	O
Loosely	B-Application
coupled	I-Application
,	O
below	O
.	O
</s>
<s>
Currently	O
,	O
32	O
IBM	B-Device
mainframes	I-Device
may	O
share	O
the	O
TPF	O
database	O
;	O
if	O
such	O
a	O
system	O
were	O
in	O
operation	O
,	O
it	O
would	O
be	O
called	O
32-way	O
loosely	B-Application
coupled	I-Application
.	O
</s>
<s>
The	O
simplest	O
loosely	B-Application
coupled	I-Application
system	O
would	O
be	O
two	O
IBM	B-Device
mainframes	I-Device
sharing	O
one	O
DASD	B-Application
(	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
)	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
control	O
program	O
would	O
be	O
equally	O
loaded	O
into	O
memory	O
and	O
each	O
program	O
or	O
record	O
on	O
DASD	B-Application
could	O
be	O
potentially	O
accessed	O
by	O
either	O
mainframe	B-Device
.	O
</s>
<s>
In	O
order	O
to	O
serialize	O
accesses	O
between	O
data	O
records	O
on	O
a	O
loosely	B-Application
coupled	I-Application
system	O
,	O
a	O
practice	O
known	O
as	O
record	B-Operating_System
locking	I-Operating_System
must	O
be	O
used	O
.	O
</s>
<s>
This	O
means	O
that	O
when	O
one	O
mainframe	B-Device
processor	O
obtains	O
a	O
hold	O
on	O
a	O
record	O
,	O
the	O
mechanism	O
must	O
prevent	O
all	O
other	O
processors	O
from	O
obtaining	O
the	O
same	O
hold	O
and	O
communicate	O
to	O
the	O
requesting	O
processors	O
that	O
they	O
are	O
waiting	O
.	O
</s>
<s>
Within	O
any	O
tightly	B-Operating_System
coupled	I-Operating_System
system	I-Operating_System
,	O
this	O
is	O
easy	O
to	O
manage	O
between	O
I-streams	O
via	O
the	O
use	O
of	O
the	O
Record	O
Hold	O
Table	O
.	O
</s>
<s>
However	O
,	O
when	O
the	O
lock	O
is	O
obtained	O
offboard	O
of	O
the	O
TPF	O
processor	O
in	O
the	O
DASD	B-Application
control	O
unit	O
,	O
an	O
external	O
process	O
must	O
be	O
used	O
.	O
</s>
<s>
Historically	O
,	O
the	O
record	B-Operating_System
locking	I-Operating_System
was	O
accomplished	O
in	O
the	O
DASD	B-Application
control	O
unit	O
via	O
an	O
RPQ	O
known	O
as	O
LLF	O
(	O
Limited	O
Locking	O
Facility	O
)	O
and	O
later	O
ELLF	O
(	O
extended	O
)	O
.	O
</s>
<s>
To	O
run	O
clustered	O
(	O
loosely	B-Application
coupled	I-Application
)	O
z/TPF	B-Operating_System
requires	O
either	O
MPLF	O
in	O
all	O
disk	O
control	O
units	O
or	O
an	O
alternative	O
locking	O
device	O
called	O
a	O
Coupling	O
Facility	O
.	O
</s>
<s>
Records	O
that	O
absolutely	O
must	O
be	O
managed	O
by	O
a	O
record	B-Operating_System
locking	I-Operating_System
process	O
are	O
those	O
which	O
are	O
processor	O
shared	O
.	O
</s>
<s>
Given	O
a	O
record	O
type	O
in	O
the	O
TPF	O
system	O
of	O
'	O
FRED	O
 '	O
with	O
100	O
records	O
or	O
ordinals	O
,	O
in	O
a	O
processor	O
shared	O
scheme	O
,	O
record	O
type	O
'	O
FRED	O
 '	O
ordinal	O
'	O
5	O
 '	O
would	O
resolve	O
to	O
exactly	O
the	O
same	O
file	O
address	O
on	O
DASD	B-Application
—	O
necessitating	O
the	O
use	O
of	O
a	O
record	B-Operating_System
locking	I-Operating_System
mechanism	O
.	O
</s>
<s>
A	O
processor	O
unique	O
record	O
is	O
one	O
that	O
is	O
defined	O
such	O
that	O
each	O
processor	O
expected	O
to	O
be	O
in	O
the	O
loosely	B-Application
coupled	I-Application
complex	O
has	O
a	O
record	O
type	O
of	O
'	O
FRED	O
 '	O
and	O
perhaps	O
100	O
ordinals	O
.	O
</s>
<s>
TPF	O
has	O
no	O
built-in	O
graphical	O
user	O
interface	O
functionality	O
,	O
and	O
TPF	O
has	O
never	O
offered	O
direct	O
graphical	O
display	O
facilities	O
:	O
to	O
implement	O
it	O
on	O
the	O
host	O
would	O
be	O
considered	O
an	O
unnecessary	O
and	O
potentially	O
harmful	O
diversion	O
of	O
real-time	B-Operating_System
system	O
resources	O
.	O
</s>
<s>
All	O
work	O
is	O
accomplished	O
via	O
the	O
use	O
of	O
the	O
command	O
line	O
,	O
similar	O
to	O
UNIX	B-Application
without	O
X	B-Operating_System
.	O
</s>
<s>
Being	O
a	O
specialized	O
purpose	O
operating	O
system	O
,	O
TPF	O
does	O
not	O
host	O
a	O
compiler/assembler	O
,	O
text	O
editor	O
,	O
nor	O
implement	O
the	O
concept	O
of	O
a	O
desktop	O
as	O
one	O
might	O
expect	O
to	O
find	O
in	O
a	O
general-purpose	O
operating	O
system	O
.	O
</s>
<s>
Starting	O
with	O
z/TPF	B-Operating_System
1.1	O
,	O
Linux	B-Application
is	O
the	O
supported	O
build	O
platform	O
;	O
executable	O
programs	O
intended	O
for	O
z/TPF	B-Operating_System
operation	O
must	O
observe	O
the	O
ELF	O
format	O
for	O
s390x-ibm-linux	O
.	O
</s>
<s>
TPF	O
implements	O
debugging	O
in	O
a	O
distributed	O
client-server	O
mode	O
,	O
which	O
is	O
necessary	O
because	O
of	O
the	O
system	O
's	O
headless	O
,	O
multi-processing	B-Operating_System
nature	O
:	O
pausing	O
the	O
entire	O
system	O
in	O
order	O
to	O
trap	O
a	O
single	O
task	O
would	O
be	O
highly	O
counterproductive	O
.	O
</s>
<s>
IBM	O
's	O
debugging	O
client	O
offering	O
is	O
packaged	O
in	O
an	O
IDE	B-Application
called	O
IBM	O
TPF	O
Toolkit	O
.	O
</s>
<s>
This	O
was	O
due	O
in	O
part	O
to	O
the	O
physical	O
record	O
sizes	O
of	O
blocks	O
located	O
on	O
DASD	B-Application
.	O
</s>
<s>
In	O
fact	O
,	O
only	O
because	O
of	O
legacy	O
support	O
are	O
smaller-than-4K	O
DASD	B-Application
records	O
still	O
used	O
.	O
</s>
<s>
With	O
the	O
advances	O
made	O
in	O
DASD	B-Application
technology	O
,	O
a	O
read/write	O
of	O
a	O
4K	O
record	O
is	O
just	O
as	O
efficient	O
as	O
a	O
1055	O
byte	O
record	O
.	O
</s>
<s>
For	O
the	O
first	O
forty	O
years	O
of	O
TPF	O
's	O
history	O
,	O
these	O
segments	O
were	O
never	O
link-edited	B-Application
.	O
</s>
<s>
Instead	O
,	O
the	O
relocatable	O
object	O
code	O
(	O
direct	O
output	O
from	O
the	O
assembler	B-Language
)	O
was	O
laid	O
out	O
in	O
memory	O
,	O
had	O
its	O
internally	O
(	O
self-referential	O
)	O
relocatable	O
symbols	O
resolved	O
,	O
then	O
the	O
entire	O
image	O
was	O
written	O
to	O
file	O
for	O
later	O
loading	O
into	O
the	O
system	O
.	O
</s>
<s>
This	O
created	O
a	O
challenging	O
programming	B-Application
environment	I-Application
in	O
which	O
segments	O
related	O
to	O
one	O
another	O
could	O
not	O
directly	O
address	O
each	O
other	O
,	O
with	O
control	O
transfer	O
between	O
them	O
implemented	O
as	O
the	O
ENTER/BACK	O
system	O
service	O
.	O
</s>
<s>
The	O
introduction	O
of	O
C	B-Language
language	I-Language
to	O
TPF	O
at	O
version	O
3.0	O
was	O
first	O
implemented	O
conformant	O
to	O
segment	O
conventions	O
,	O
including	O
the	O
absence	O
of	O
linkage	O
editing	O
.	O
</s>
<s>
This	O
scheme	O
quickly	O
demonstrated	O
itself	O
to	O
be	O
impractical	O
for	O
anything	O
other	O
than	O
the	O
simplest	O
of	O
C	B-Language
programs	I-Language
.	O
</s>
<s>
These	O
were	O
compiled	O
with	O
the	O
z/OS	B-Application
C/C	O
++	O
compiler	O
using	O
TPF-specific	O
header	B-Language
files	I-Language
and	O
linked	O
with	O
IEWL	O
,	O
resulting	O
in	O
a	O
z/OS	B-Application
-conformant	O
load	O
module	O
,	O
which	O
in	O
no	O
manner	O
could	O
be	O
considered	O
a	O
traditional	O
TPF	O
segment	O
.	O
</s>
<s>
The	O
TPF	O
loader	O
was	O
extended	O
to	O
read	O
the	O
z/OS	B-Application
-unique	O
load	O
module	O
file	O
format	O
,	O
then	O
lay	O
out	O
file-resident	O
load	O
modules	O
 '	O
sections	O
into	O
memory	O
;	O
meanwhile	O
,	O
assembly	B-Language
language	I-Language
programs	O
remained	O
confined	O
to	O
TPF	O
's	O
segment	O
model	O
,	O
creating	O
an	O
obvious	O
disparity	O
between	O
applications	O
written	O
in	O
assembler	B-Language
and	O
those	O
written	O
in	O
higher	O
level	O
languages	O
(	O
HLL	O
)	O
.	O
</s>
<s>
At	O
z/TPF	B-Operating_System
1.1	O
,	O
all	O
source	O
language	O
types	O
were	O
conceptually	O
unified	O
and	O
fully	O
link-edited	B-Application
to	O
conform	O
to	O
the	O
ELF	O
specification	O
.	O
</s>
<s>
The	O
segment	O
concept	O
became	O
obsolete	O
,	O
meaning	O
that	O
any	O
program	O
written	O
in	O
any	O
source	O
language	O
—	O
including	O
Assembler	B-Language
—	O
may	O
now	O
be	O
of	O
any	O
size	O
.	O
</s>
<s>
Members	O
of	O
the	O
same	O
shared	O
object	O
may	O
now	O
share	O
writeable	O
data	O
regions	O
directly	O
thanks	O
to	O
copy-on-write	B-Language
functionality	O
also	O
introduced	O
at	O
z/TPF	B-Operating_System
1.1	O
;	O
which	O
coincidentally	O
reinforces	O
TPF	O
's	O
reentrancy	B-Operating_System
requirements	O
.	O
</s>
<s>
The	O
concepts	O
of	O
file	O
-	O
and	O
memory	O
-	O
residency	O
were	O
also	O
made	O
obsolete	O
,	O
due	O
to	O
a	O
z/TPF	B-Operating_System
design	O
point	O
which	O
sought	O
to	O
have	O
all	O
programs	O
resident	O
in	O
memory	O
at	O
all	O
times	O
.	O
</s>
<s>
Since	O
z/TPF	B-Operating_System
had	O
to	O
maintain	O
a	O
call	B-General_Concept
stack	I-General_Concept
for	O
high-level	O
language	O
programs	O
,	O
which	O
gave	O
HLL	O
programs	O
the	O
ability	O
to	O
benefit	O
from	O
stack-based	B-General_Concept
memory	I-General_Concept
allocation	I-General_Concept
,	O
it	O
was	O
deemed	O
beneficial	O
to	O
extend	O
the	O
call	B-General_Concept
stack	I-General_Concept
to	O
assembly	B-Language
language	I-Language
programs	O
on	O
an	O
optional	O
basis	O
,	O
which	O
can	O
ease	O
memory	O
pressure	O
and	O
ease	O
recursive	O
programming	O
.	O
</s>
<s>
All	O
z/TPF	B-Operating_System
executable	O
programs	O
are	O
now	O
packaged	O
as	O
ELF	O
shared	O
objects	O
.	O
</s>
<s>
As	O
applications	O
got	O
more	O
advanced	O
demands	O
for	O
memory	O
increased	O
,	O
and	O
once	O
C	B-Language
became	O
available	O
memory	O
chunks	O
of	O
indeterminate	O
or	O
large	O
size	O
were	O
required	O
.	O
</s>
<s>
To	O
ease	O
the	O
overhead	O
,	O
TPF	O
memory	O
was	O
broken	O
into	O
frames	O
—	O
4KB	O
in	O
size	O
(	O
1MB	O
with	O
z/TPF	B-Operating_System
)	O
.	O
</s>
