<s>
OS/360	B-Application
,	O
officially	O
known	O
as	O
IBM	B-Application
System/360	I-Application
Operating	I-Application
System	I-Application
,	O
is	O
a	O
discontinued	O
batch	B-General_Concept
processing	I-General_Concept
operating	B-General_Concept
system	I-General_Concept
developed	O
by	O
IBM	O
for	O
their	O
then-new	O
System/360	B-Application
mainframe	B-Architecture
computer	I-Architecture
,	O
announced	O
in	O
1964	O
;	O
it	O
was	O
influenced	O
by	O
the	O
earlier	O
IBSYS/IBJOB	B-Operating_System
and	O
Input/Output	B-Application
Control	I-Application
System	I-Application
(	O
IOCS	B-Application
)	O
packages	O
for	O
the	O
IBM	B-Device
7090/7094	I-Device
and	O
even	O
more	O
so	O
by	O
the	O
PR155	O
Operating	B-General_Concept
System	I-General_Concept
for	O
the	O
IBM	O
1410/7010	O
processors	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
earliest	O
operating	B-General_Concept
systems	I-General_Concept
to	O
require	O
the	O
computer	O
hardware	O
to	O
include	O
at	O
least	O
one	O
direct	B-Application
access	I-Application
storage	I-Application
device	I-Application
.	O
</s>
<s>
Although	O
OS/360	B-Application
itself	O
was	O
discontinued	O
,	O
successor	O
operating	B-General_Concept
systems	I-General_Concept
,	O
including	O
the	O
virtual	B-Architecture
storage	I-Architecture
MVS	B-Application
and	O
the	O
64-bit	B-Device
z/OS	B-Application
,	O
are	O
still	O
run	O
and	O
maintain	O
application-level	O
compatibility	O
with	O
OS/360	B-Application
.	O
</s>
<s>
IBM	O
announced	O
three	O
different	O
levels	O
of	O
OS/360	B-Application
,	O
generated	O
from	O
the	O
same	O
tapes	O
and	O
sharing	O
most	O
of	O
their	O
code	O
.	O
</s>
<s>
Users	O
often	O
coined	O
nicknames	O
,	O
e.g.	O
,	O
"	O
Big	O
OS	O
"	O
,	O
"	O
OS/MFT	B-Application
"	O
,	O
but	O
none	O
of	O
these	O
names	O
had	O
any	O
official	O
recognition	O
by	O
IBM	O
.	O
</s>
<s>
IBM	O
provided	O
OS/360	B-Application
as	O
a	O
set	O
of	O
libraries	O
on	O
tape	O
that	O
the	O
installation	O
had	O
to	O
restore	O
to	O
DASD	B-Application
in	O
order	O
to	O
perform	O
a	O
system	B-Application
generation	I-Application
.	O
</s>
<s>
The	O
other	O
major	O
operating	B-General_Concept
system	I-General_Concept
for	O
System/360	B-Application
hardware	O
was	O
DOS/360	O
.	O
</s>
<s>
OS/360	B-Application
is	O
in	O
the	O
public	O
domain	O
and	O
can	O
be	O
downloaded	O
freely	O
.	O
</s>
<s>
As	O
well	O
as	O
being	O
run	O
on	O
actual	O
System/360	B-Application
hardware	O
,	O
it	O
can	O
be	O
executed	O
on	O
the	O
free	O
Hercules	B-Application
emulator	I-Application
,	O
which	O
runs	O
under	O
most	O
UNIX	B-Application
and	O
Unix-like	B-Operating_System
systems	I-Operating_System
including	O
Linux	B-Application
,	O
Solaris	B-Application
,	O
and	O
macOS	B-Application
,	O
as	O
well	O
as	O
Windows	B-Application
.	O
</s>
<s>
There	O
are	O
OS/360	B-Application
turnkey	O
CDs	O
that	O
provide	O
pregenerated	O
OS/360	B-Application
21.8	O
systems	O
ready	O
to	O
run	O
under	O
Hercules	B-Application
.	O
</s>
<s>
IBM	O
originally	O
intended	O
that	O
System/360	B-Application
should	O
have	O
only	O
one	O
batch-oriented	B-General_Concept
operating	B-General_Concept
system	I-General_Concept
,	O
OS/360	B-Application
,	O
capable	O
of	O
running	O
on	O
machines	O
as	O
small	O
as	O
32KiB	O
.	O
</s>
<s>
It	O
also	O
intended	O
to	O
supply	O
a	O
separate	O
timesharing	B-General_Concept
operating	B-General_Concept
system	I-General_Concept
,	O
TSS/360	B-Application
,	O
for	O
the	O
System/360	B-Device
Model	I-Device
67	I-Device
.	O
</s>
<s>
There	O
are	O
at	O
least	O
two	O
accounts	O
of	O
why	O
IBM	O
eventually	O
decided	O
to	O
produce	O
other	O
,	O
simpler	O
batch-oriented	B-General_Concept
operating	B-General_Concept
systems	I-General_Concept
:	O
</s>
<s>
because	O
it	O
realized	O
that	O
the	O
development	O
of	O
OS/360	B-Application
would	O
take	O
much	O
longer	O
than	O
expected	O
.	O
</s>
<s>
IBM	O
introduced	O
a	O
series	O
of	O
stop-gaps	O
to	O
prevent	O
System/360	B-Application
hardware	O
sales	O
from	O
collapsingfirst	O
Basic	B-Application
Programming	I-Application
Support	I-Application
(	O
BPS	O
)	O
and	O
BOS/360	B-Application
(	O
Basic	B-Application
Operating	I-Application
System	I-Application
,	O
for	O
the	O
smallest	O
machines	O
with	O
8K	O
byte	O
memories	O
)	O
,	O
then	O
TOS/360	O
(	O
Tape	O
Operating	B-General_Concept
System	I-General_Concept
,	O
for	O
machines	O
with	O
at	O
least	O
16K	O
byte	O
memories	O
and	O
only	O
tape	O
drives	O
)	O
,	O
and	O
finally	O
DOS/360	O
(	O
Disk	O
Operating	B-General_Concept
System	I-General_Concept
)	O
,	O
which	O
became	O
a	O
mainstream	O
operating	B-General_Concept
system	I-General_Concept
and	O
is	O
the	O
ancestor	O
of	O
today	O
's	O
widely	O
used	O
z/VSE	B-Application
.	O
</s>
<s>
IBM	O
released	O
three	O
variants	O
of	O
OS/360	B-Application
:	O
PCP	O
(	O
Primary	O
Control	O
Program	O
)	O
,	O
a	O
stop-gap	O
which	O
could	O
run	O
only	O
one	O
job	O
at	O
a	O
time	O
,	O
in	O
1966	O
;	O
MFT	O
(	O
Multiprogramming	O
with	O
Fixed	O
number	O
of	O
Tasks	O
)	O
for	O
the	O
mid-range	O
machines	O
,	O
and	O
MVT	O
(	O
Multiprogramming	O
with	O
Variable	O
number	O
of	O
Tasks	O
)	O
for	O
the	O
top	O
end	O
.	O
</s>
<s>
Initially	O
IBM	O
maintained	O
that	O
MFT	O
and	O
MVT	O
were	O
simply	O
"	O
two	O
configurations	O
of	O
the	O
OS/360	B-Application
control	O
program	O
"	O
,	O
although	O
later	O
IBM	O
described	O
them	O
as	O
"	O
separate	O
versions	O
of	O
OS/360	B-Application
"	O
.	O
</s>
<s>
IBM	O
originally	O
wrote	O
OS/360	B-Application
in	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Later	O
on	O
,	O
IBM	O
wrote	O
some	O
OS/360	B-Application
code	O
in	O
a	O
new	O
language	O
,	O
Basic	B-Language
Systems	I-Language
Language	I-Language
(	O
BSL	O
)	O
,	O
derived	O
from	O
PL/I	B-Language
.	O
</s>
<s>
A	O
large	O
amount	O
of	O
the	O
TSO	B-Application
code	O
in	O
Release	O
20	O
was	O
written	O
in	O
BSL	O
.	O
</s>
<s>
TSS/360	B-Application
was	O
so	O
late	O
and	O
unreliable	O
that	O
IBM	O
canceled	O
it	O
,	O
although	O
IBM	O
later	O
supplied	O
three	O
releases	O
of	O
the	O
TSS/370	B-Application
PRPQ	O
.	O
</s>
<s>
By	O
this	O
time	O
CP-67	B-Application
was	O
running	O
well	O
enough	O
for	O
IBM	O
to	O
offer	O
it	O
without	O
warranty	O
as	O
a	O
timesharing	B-General_Concept
facility	O
for	O
a	O
few	O
large	O
customers	O
.	O
</s>
<s>
These	O
three	O
options	O
offered	O
such	O
similar	O
facilities	O
that	O
porting	O
applications	O
between	O
them	O
usually	O
required	O
minimal	O
effort	O
;	O
the	O
same	O
versions	O
of	O
IBM	O
Program	O
Products	O
,	O
application	O
and	O
utility	B-Application
software	O
ran	O
on	O
both	O
.	O
</s>
<s>
Officially	O
,	O
PCP	O
,	O
MFT	O
and	O
MVT	O
are	O
not	O
separate	O
operating	B-General_Concept
systems	I-General_Concept
from	O
OS/360	B-Application
,	O
they	O
are	O
only	O
install-time	O
configuration	O
optionsin	O
today	O
's	O
words	O
,	O
three	O
different	O
variants	O
of	O
the	O
OS	O
Nucleus	O
and	O
Scheduler	O
.	O
</s>
<s>
However	O
,	O
because	O
of	O
quite	O
different	O
behavior	O
and	O
memory	O
requirements	O
,	O
users	O
commonly	O
consider	O
them	O
de	O
facto	O
separate	O
operating	B-General_Concept
systems	I-General_Concept
and	O
refer	O
to	O
them	O
as	O
"	O
early	O
OS/360	B-Application
"	O
,	O
"	O
OS/MFT	B-Application
"	O
,	O
"	O
OS/MVT	O
"	O
,	O
respectively	O
.	O
</s>
<s>
MFT	O
differs	O
from	O
MVT	O
mainly	O
in	O
the	O
way	O
in	O
which	O
it	O
manages	O
memory	O
:	O
when	O
installing	O
MFT	O
,	O
customers	O
specify	O
in	O
the	O
system	B-Application
generation	I-Application
(	O
SysGen	B-Application
)	O
a	O
fixed	O
number	O
of	O
partitions	O
,	O
areas	O
of	O
memory	O
with	O
fixed	O
boundaries	O
,	O
in	O
which	O
application	O
programs	O
can	O
be	O
run	O
simultaneously	O
.	O
</s>
<s>
Experience	O
indicated	O
that	O
it	O
was	O
not	O
advisable	O
to	O
install	O
OS/360	B-Application
on	O
systems	O
with	O
less	O
than	O
128KiB	O
of	O
memory	O
,	O
although	O
limited	O
production	O
use	O
was	O
possible	O
on	O
much	O
smaller	O
machines	O
,	O
such	O
as	O
48KiB	O
of	O
memory	O
.	O
</s>
<s>
IBM	O
dropped	O
the	O
PCP	O
option	O
in	O
the	O
final	O
releases	O
of	O
OS/360	B-Application
,	O
leaving	O
only	O
MFT	O
II	O
and	O
MVT	O
,	O
both	O
of	O
which	O
required	O
more	O
memory	O
.	O
</s>
<s>
Multiprogramming	O
with	O
a	O
Fixed	O
number	O
of	O
Tasks	O
(	O
MFT	O
)	O
was	O
intended	O
to	O
serve	O
as	O
a	O
stop-gap	O
until	O
Multiprogramming	O
with	O
a	O
Variable	O
number	O
of	O
Tasks	O
(	O
MVT	O
)	O
,	O
the	O
intended	O
target	O
configuration	O
of	O
OS/360	B-Application
,	O
became	O
available	O
in	O
1967	O
.	O
</s>
<s>
After	O
introducing	O
new	O
System/370	B-Device
machines	O
with	O
virtual	B-Architecture
memory	I-Architecture
in	O
1972	O
,	O
IBM	O
developed	O
MFT2	O
into	O
OS/VS1	B-Application
,	O
the	O
last	O
system	O
of	O
this	O
particular	O
line	O
.	O
</s>
<s>
Many	O
installations	O
used	O
Houston	B-Application
Automatic	I-Application
Spooling	I-Application
Priority	I-Application
(	O
HASP	O
)	O
to	O
mitigate	O
the	O
complexity	O
.	O
</s>
<s>
Multiprogramming	O
with	O
a	O
Variable	O
number	O
of	O
Tasks	O
(	O
MVT	O
)	O
was	O
the	O
most	O
sophisticated	O
of	O
three	O
available	O
configurations	O
of	O
OS/360	B-Application
'	O
s	O
control	O
program	O
,	O
and	O
one	O
of	O
two	O
available	O
configurations	O
in	O
the	O
final	O
releases	O
.	O
</s>
<s>
MVT	O
was	O
intended	O
for	O
the	O
largest	O
machines	O
in	O
the	O
System/360	B-Application
family	O
.	O
</s>
<s>
MVT	O
treated	O
all	O
memory	O
not	O
used	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
as	O
a	O
single	O
pool	O
from	O
which	O
contiguous	O
regions	O
could	O
be	O
allocated	O
as	O
required	O
by	O
an	O
unlimited	O
number	O
of	O
simultaneous	O
application	O
and	O
systems	O
programs	O
.	O
</s>
<s>
This	O
scheme	O
was	O
more	O
flexible	O
than	O
MFT	O
's	O
and	O
in	O
principle	O
used	O
memory	O
more	O
efficiently	O
,	O
but	O
was	O
liable	O
to	O
fragmentation	B-Architecture
-	O
after	O
a	O
while	O
one	O
could	O
find	O
that	O
,	O
although	O
there	O
was	O
enough	O
spare	O
memory	O
in	O
total	O
to	O
run	O
a	O
program	O
,	O
it	O
was	O
divided	O
into	O
separate	O
chunks	O
none	O
of	O
which	O
was	O
large	O
enough	O
.	O
</s>
<s>
System/360	B-Application
lacked	O
memory	O
relocation	O
hardware	O
so	O
memory	O
compaction	O
could	O
not	O
be	O
used	O
to	O
reduce	O
fragmentation	B-Architecture
.	O
</s>
<s>
In	O
1971	O
the	O
Time	B-Application
Sharing	I-Application
Option	I-Application
(	O
TSO	B-Application
)	O
for	O
use	O
with	O
MVT	O
was	O
added	O
as	O
part	O
of	O
release	O
20.1	O
.	O
</s>
<s>
TSO	B-Application
became	O
widely	O
used	O
for	O
program	O
development	O
because	O
it	O
provided	O
an	O
editor	O
,	O
the	O
ability	O
to	O
submit	O
batch	B-General_Concept
jobs	I-General_Concept
,	O
be	O
notified	O
of	O
their	O
completion	O
,	O
and	O
view	O
the	O
results	O
without	O
waiting	O
for	O
printed	O
reports	O
,	O
and	O
debuggers	B-Application
for	O
some	O
of	O
the	O
programming	O
languages	O
used	O
on	O
System/360	B-Application
.	O
</s>
<s>
TSO	B-Application
in	O
OS/360	B-Application
communicated	O
with	O
terminals	O
by	O
using	O
Telecommunications	B-Application
Access	I-Application
Method	I-Application
(	O
TCAM	O
)	O
.	O
</s>
<s>
TCAM	O
's	O
name	O
suggests	O
that	O
IBM	O
hoped	O
it	O
would	O
become	O
the	O
standard	O
access	B-Application
method	I-Application
for	O
data	O
communications	O
,	O
but	O
in	O
fact	O
TCAM	O
in	O
OS/VS2	B-Application
was	O
used	O
almost	O
entirely	O
for	O
TSO	B-Application
and	O
was	O
largely	O
superseded	O
by	O
Virtual	B-Application
Telecommunications	I-Application
Access	I-Application
Method	I-Application
(	O
VTAM	B-Application
)	O
in	O
the	O
mid-to-late	O
1970s	O
.	O
</s>
<s>
Also	O
referred	O
to	O
as	O
SYS	O
=	O
VMS	B-Application
in	O
invocations	O
of	O
some	O
macros	O
that	O
were	O
system-dependent	O
.	O
</s>
<s>
The	O
keyword	O
parameter	O
SYS	O
=	O
VMS	B-Application
included	O
M65MP	O
as	O
well	O
as	O
uniprocessor	O
MVT	O
.	O
</s>
<s>
The	O
same	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
and	O
application	B-Operating_System
binary	I-Operating_System
interface	I-Operating_System
(	O
ABI	O
)	O
,	O
so	O
application	O
programs	O
can	O
be	O
transferred	O
between	O
MFT	O
and	O
MVT	O
without	O
even	O
needing	O
to	O
be	O
modified	O
or	O
re-assembled	B-Language
or	O
re-compiled	B-Language
.	O
</s>
<s>
The	O
same	O
JCL	B-Application
(	O
Job	B-Application
Control	I-Application
Language	I-Application
,	O
for	O
initiating	O
batch	B-General_Concept
jobs	I-General_Concept
)	O
,	O
which	O
was	O
more	O
flexible	O
and	O
easier	O
to	O
use	O
,	O
though	O
more	O
complex	O
,	O
than	O
that	O
of	O
DOS/360	O
.	O
</s>
<s>
The	O
same	O
facilities	O
(	O
access	B-Application
methods	I-Application
)	O
for	O
reading	O
and	O
writing	O
files	O
and	O
for	O
data	O
communications	O
:	O
</s>
<s>
Sequential	O
data	O
sets	O
are	O
normally	O
read	O
or	O
written	O
one	O
record	O
at	O
a	O
time	O
from	O
beginning	O
to	O
end	O
,	O
using	O
BSAM	B-Application
or	O
QSAM	B-Application
.	O
</s>
<s>
This	O
was	O
the	O
only	O
technique	O
that	O
could	O
be	O
used	O
for	O
tape	O
drives	O
,	O
card	B-Architecture
readers	O
/	O
punches	O
and	O
printers	O
.	O
</s>
<s>
In	O
indexed	O
(	O
ISAM	B-Application
)	O
files	O
a	O
specified	O
section	O
of	O
each	O
record	O
is	O
defined	O
as	O
a	O
key	O
which	O
can	O
be	O
used	O
to	O
look	O
up	O
specific	O
records	O
.	O
</s>
<s>
In	O
direct	O
access	O
(	O
BDAM	B-Application
)	O
files	O
,	O
the	O
application	O
program	O
has	O
to	O
specify	O
the	O
relative	O
block	O
number	O
,	O
the	O
relative	O
track	O
and	O
record	O
(	O
TTR	O
)	O
or	O
the	O
actual	O
physical	O
location	O
(	O
MBBCCHHR	O
)	O
in	O
a	O
Direct-access	B-Application
storage	I-Application
device	I-Application
(	O
DASD	B-Application
)	O
of	O
the	O
data	O
it	O
wanted	O
to	O
access	O
,	O
or	O
the	O
starting	O
point	O
for	O
a	O
search	O
by	O
key	O
.	O
</s>
<s>
BDAM	B-Application
programming	O
was	O
not	O
easy	O
and	O
most	O
organizations	O
never	O
used	O
it	O
themselves	O
;	O
but	O
it	O
was	O
the	O
fastest	O
way	O
to	O
access	O
data	O
on	O
disks	O
and	O
many	O
software	O
companies	O
used	O
it	O
in	O
their	O
products	O
,	O
especially	O
database	B-Application
management	I-Application
systems	I-Application
such	O
as	O
ADABAS	B-Application
,	O
IDMS	B-Application
and	O
IBM	O
's	O
DL/I	B-Language
.	O
</s>
<s>
It	O
is	O
also	O
available	O
from	O
OS/360	B-Application
Fortran	O
.	O
</s>
<s>
BDAM	B-Application
datasets	O
are	O
unblocked	O
,	O
with	O
one	O
logical	O
record	O
per	O
physical	O
record	O
.	O
</s>
<s>
An	O
additional	O
file	O
structure	O
,	O
partitioned	O
,	O
and	O
access	B-Application
method	I-Application
(	O
BPAM	B-Application
)	O
,	O
is	O
mainly	O
used	O
for	O
managing	O
program	O
libraries	O
.	O
</s>
<s>
But	O
one	O
could	O
set	O
up	O
GDGs	O
with	O
more	O
than	O
3	O
generations	O
,	O
and	O
some	O
applications	O
used	O
GDGs	O
to	O
collect	O
data	O
from	O
large	O
and	O
variable	O
numbers	O
of	O
sources	O
and	O
feed	O
the	O
information	O
to	O
one	O
program	O
-	O
each	O
collecting	O
program	O
created	O
a	O
new	O
generation	O
of	O
the	O
file	O
and	O
the	O
final	O
program	O
read	O
the	O
whole	O
group	O
as	O
a	O
single	O
sequential	O
file	O
(	O
by	O
not	O
specifying	O
a	O
generation	O
in	O
the	O
JCL	B-Application
)	O
.	O
</s>
<s>
BTAM	B-Application
,	O
a	O
data	O
communications	O
facility	O
,	O
was	O
primitive	O
and	O
hard	O
to	O
use	O
by	O
today	O
's	O
standards	O
.	O
</s>
<s>
A	O
SPOOLing	B-Device
facility	O
for	O
MFT	O
II	O
and	O
MVT	O
(	O
which	O
DOS/360	O
initially	O
lacked	O
,	O
but	O
was	O
,	O
later	O
,	O
provided	O
by	O
the	O
POWER	O
application	O
)	O
.	O
</s>
<s>
Applications	O
in	O
MFT	O
(	O
Release	O
19	O
and	O
later	O
)	O
and	O
MVT	O
could	O
create	O
sub-tasks	O
,	O
which	O
allowed	O
multitasking	O
(	O
multithreading	B-Operating_System
)	O
within	O
the	O
one	O
job	O
.	O
</s>
<s>
When	O
System/370	B-Device
was	O
announced	O
in	O
1970	O
it	O
offered	O
essentially	O
the	O
same	O
facilities	O
as	O
System/360	B-Application
but	O
with	O
about	O
4	O
times	O
the	O
processor	O
speeds	O
of	O
similarly	O
priced	O
System/360	B-Application
CPUs	O
.	O
</s>
<s>
Then	O
in	O
1972	O
IBM	O
announced	O
System/370	B-Device
Advanced	O
Functions	O
,	O
of	O
which	O
the	O
main	O
item	O
was	O
that	O
future	O
sales	O
of	O
System/370	B-Device
would	O
include	O
virtual	B-Architecture
memory	I-Architecture
capability	O
and	O
this	O
could	O
also	O
be	O
retro-fitted	O
to	O
existing	O
System/370	B-Device
CPUs	O
.	O
</s>
<s>
Hence	O
IBM	O
also	O
committed	O
to	O
delivering	O
enhanced	O
operating	B-General_Concept
systems	I-General_Concept
which	O
could	O
support	O
the	O
use	O
of	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
IBM	O
provided	O
an	O
OS/360	B-Application
SYSGEN	B-Application
option	O
for	O
S/370	B-Device
support	O
,	O
which	O
did	O
not	O
support	O
DAT	O
but	O
did	O
:	O
</s>
<s>
OS/VS1	B-Application
is	O
the	O
successor	O
to	O
MFT	O
,	O
and	O
offers	O
similar	O
facilities	O
with	O
several	O
additions	O
,	O
e.g.	O
,	O
RES	O
,	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
VSAM	O
(	O
see	O
below	O
)	O
was	O
initially	O
available	O
as	O
an	O
independent	O
component	O
release	O
(	O
ICR	O
)	O
and	O
later	O
integrated	O
into	O
the	O
OS/VS1	B-Application
base	O
.	O
</s>
<s>
IBM	O
released	O
fairly	O
minor	O
enhancements	O
of	O
OS/VS1	B-Application
until	O
1983	O
,	O
and	O
in	O
1984	O
announced	O
that	O
there	O
would	O
be	O
no	O
more	O
.	O
</s>
<s>
AIX/370	O
,	O
AIX/ESA	O
,	O
DPPX	B-Operating_System
,	O
IX/370	O
,	O
OS/VS1	B-Application
and	O
TSS/370	B-Application
are	O
the	O
only	O
System/370	B-Device
operating	B-General_Concept
systems	I-General_Concept
that	O
do	O
not	O
have	O
modern	O
descendants	O
.	O
</s>
<s>
OS/VS2	B-Application
release	O
1	O
was	O
just	O
MVT	O
plus	O
virtual	B-Architecture
memory	I-Architecture
and	O
VSAM	O
(	O
see	O
below	O
)	O
.	O
</s>
<s>
This	O
version	O
was	O
eventually	O
renamed	O
OS/VS2	B-Application
SVS	I-Application
,	O
for	O
Single	O
Virtual	B-Architecture
Storage	I-Architecture
,	O
when	O
OS/VS2	B-Application
Release	O
2	O
,	O
also	O
known	O
as	O
MVS	B-Application
,	O
for	O
Multiple	B-Application
Virtual	I-Application
Storage	I-Application
,	O
was	O
introduced	O
.	O
</s>
<s>
SVS	B-Application
was	O
intended	O
as	O
a	O
stepping	O
stone	O
from	O
MVT	O
to	O
MVS	B-Application
,	O
and	O
is	O
only	O
of	O
historical	O
interest	O
today	O
.	O
</s>
<s>
In	O
1974	O
IBM	O
released	O
what	O
it	O
described	O
as	O
OS/VS2	B-Application
Release	O
2	O
but	O
which	O
was	O
really	O
a	O
new	O
operating	B-General_Concept
system	I-General_Concept
that	O
was	O
upwards-compatible	B-General_Concept
with	O
OS/VS2	B-Application
Release	O
1	O
.	O
</s>
<s>
The	O
Supervisor	O
of	O
the	O
new	O
system	O
had	O
been	O
largely	O
rewritten	O
in	O
a	O
new	O
dialect	O
of	O
BSL	O
,	O
PL/S	B-Language
;	O
BSL	O
and	O
PL/S	B-Language
were	O
dialects	O
of	O
PL/I	B-Language
with	O
extensions	O
designed	O
to	O
transcribe	O
Assembly	B-Language
language	I-Language
code	O
,	O
including	O
privileged	O
instructions	O
needed	O
to	O
control	O
the	O
computer	O
as	O
a	O
whole	O
.	O
</s>
<s>
Time-sensitive	O
OS	O
components	O
,	O
such	O
as	O
the	O
OS	O
Dispatcher	O
and	O
the	O
IOS	B-Application
,	O
notably	O
,	O
among	O
many	O
others	O
,	O
remained	O
coded	O
in	O
Assembly	B-Language
Language	I-Language
,	O
which	O
had	O
been	O
enhanced	O
for	O
OS/VS	O
in	O
the	O
IFOX00	O
Assembler	B-Language
(	O
from	O
the	O
older	O
,	O
OS/360	B-Application
IEUASM	O
Assembler	B-Language
)	O
.	O
</s>
<s>
The	O
new	O
version	O
's	O
most	O
noticeable	O
feature	O
was	O
that	O
it	O
supported	O
multiple	O
virtual	B-General_Concept
address	I-General_Concept
spaces	I-General_Concept
-	O
different	O
applications	O
thought	O
they	O
were	O
using	O
the	O
same	O
range	O
of	O
virtual	O
addresses	O
,	O
but	O
the	O
new	O
system	O
's	O
virtual	B-Architecture
memory	I-Architecture
facilities	O
mapped	O
these	O
to	O
different	O
ranges	O
of	O
real	O
memory	O
addresses	O
.	O
</s>
<s>
Each	O
application	O
's	O
address	O
space	O
consists	O
of	O
3	O
areas	O
:	O
operating	B-General_Concept
system	I-General_Concept
(	O
one	O
instance	O
shared	O
by	O
all	O
jobs	O
)	O
;	O
an	O
application	O
area	O
which	O
was	O
unique	O
for	O
each	O
application	O
;	O
shared	O
virtual	O
area	O
used	O
for	O
various	O
purposes	O
including	O
inter-job	O
communication	O
.	O
</s>
<s>
This	O
approach	O
eliminated	O
the	O
risk	O
of	O
memory	B-Architecture
fragmentation	I-Architecture
that	O
was	O
present	O
in	O
MVT	O
and	O
SVS	B-Application
,	O
and	O
improved	O
the	O
system	O
's	O
internal	O
security	O
.	O
</s>
<s>
The	O
new	O
system	O
rapidly	O
became	O
known	O
as	O
"	O
MVS	B-Application
"	O
(	O
Multiple	B-Application
Virtual	I-Application
Storages	I-Application
)	O
,	O
the	O
original	O
OS/VS2	B-Application
became	O
known	O
as	O
"	O
SVS	B-Application
"	O
(	O
Single	O
Virtual	B-Architecture
Storage	I-Architecture
)	O
and	O
IBM	O
itself	O
accepted	O
this	O
terminology	O
and	O
labelled	O
MVS	B-Application
's	O
successors	O
"	O
MVS/xxx	O
"	O
.	O
</s>
<s>
MVS	B-Application
introduced	O
a	O
new	O
approach	O
to	O
workload	O
management	O
,	O
allowing	O
users	O
to	O
define	O
performance	O
targets	O
for	O
high-priority	O
batch	B-General_Concept
jobs	I-General_Concept
.	O
</s>
<s>
MVS	B-Application
was	O
IBM	O
's	O
first	O
mainstream	O
operating	B-General_Concept
system	I-General_Concept
on	O
the	O
System/370	B-Device
to	O
support	O
what	O
IBM	O
called	O
tightly	O
coupled	O
multiprocessing	O
,	O
in	O
which	O
2	O
(	O
later	O
,	O
up	O
to	O
12	O
,	O
for	O
IBM	B-Device
mainframes	I-Device
,	O
and	O
up	O
to	O
16	O
,	O
for	O
Amdahl	O
mainframes	B-Architecture
)	O
CPUs	O
shared	O
concurrent	O
access	O
to	O
the	O
same	O
memory	O
(	O
and	O
a	O
single	O
copy	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
peripheral	O
devices	O
)	O
,	O
providing	O
greater	O
processing	O
power	O
and	O
a	O
degree	O
of	O
graceful	B-General_Concept
degradation	I-General_Concept
if	O
one	O
CPU	O
failed	O
(	O
which	O
,	O
fortunately	O
,	O
became	O
an	O
increasingly	O
rare	O
event	O
,	O
as	O
system	O
up	O
time	O
rose	O
from	O
hours	O
to	O
days	O
and	O
,	O
then	O
,	O
to	O
years	O
.	O
)	O
</s>
<s>
Initially	O
MVS	B-Application
was	O
supplied	O
with	O
a	O
job	B-General_Concept
queue	I-General_Concept
manager	O
called	O
JES2	B-Application
(	O
Job	B-Application
Entry	I-Application
Subsystem	I-Application
2	O
)	O
,	O
which	O
was	O
descended	O
from	O
HASP	O
(	O
Houston	B-Application
Automatic	I-Application
Spooling	I-Application
Priority	I-Application
)	O
and	O
also	O
supported	O
Remote	B-Protocol
Job	I-Protocol
Entry	I-Protocol
from	O
workstations	O
located	O
elsewhere	O
.	O
</s>
<s>
JES2	B-Application
can	O
only	O
manage	O
jobs	O
for	O
one	O
CPU	O
(	O
which	O
might	O
be	O
a	O
tightly	O
coupled	O
multiprocessor	O
system	O
)	O
.	O
</s>
<s>
In	O
1976	O
IBM	O
provided	O
another	O
option	O
,	O
JES3	B-Application
(	O
Job	B-Application
Entry	I-Application
Subsystem	I-Application
3	I-Application
)	O
,	O
a	O
descendant	O
of	O
ASP	O
(	O
Attached	B-Operating_System
Support	I-Operating_System
Processor	I-Operating_System
)	O
,	O
which	O
allows	O
one	O
CPU	O
to	O
manage	O
a	O
single	O
job	B-General_Concept
queue	I-General_Concept
feeding	O
work	O
to	O
several	O
physically	O
distinct	O
CPUs	O
,	O
and	O
therefore	O
allows	O
one	O
operator	O
's	O
console	O
to	O
manage	O
the	O
work	O
of	O
all	O
those	O
CPUs	O
.	O
</s>
<s>
Note	O
:	O
JES1	O
was	O
the	O
job	B-General_Concept
queue	I-General_Concept
manager	O
for	O
OS/VS1	B-Application
(	O
see	O
above	O
)	O
.	O
</s>
<s>
IBM	O
hoped	O
that	O
Virtual	B-Application
storage	I-Application
access	I-Application
method	I-Application
(	O
VSAM	O
)	O
would	O
replace	O
its	O
earlier	O
sequential	O
,	O
indexed	O
and	O
direct	O
access	B-Application
methods	I-Application
as	O
it	O
provided	O
improved	O
versions	O
of	O
these	O
:	O
</s>
<s>
Entry-Sequenced	O
Datasets	O
(	O
ESDS	O
)	O
provide	O
facilities	O
similar	O
to	O
those	O
of	O
both	O
sequential	O
and	O
BDAM	B-Application
(	O
direct	O
)	O
datasets	O
,	O
since	O
they	O
can	O
be	O
read	O
either	O
from	O
start	O
to	O
finish	O
or	O
directly	O
by	O
specifying	O
an	O
offset	O
from	O
the	O
start	O
.	O
</s>
<s>
Key-Sequenced	O
Datasets	O
(	O
KSDS	O
)	O
are	O
a	O
major	O
upgrade	O
from	O
IBM	O
's	O
ISAM	B-Application
:	O
they	O
allow	O
secondary	O
keys	O
with	O
non-unique	O
values	O
and	O
keys	O
formed	O
by	O
concatenating	O
non-contiguous	O
fields	O
in	O
any	O
order	O
;	O
they	O
greatly	O
reduce	O
the	O
performance	O
problems	O
caused	O
by	O
overflow	O
records	O
used	O
to	O
handle	O
insertions	O
and	O
updates	O
in	O
ISAM	B-Application
;	O
and	O
they	O
greatly	O
reduce	O
the	O
risk	O
that	O
a	O
software	O
or	O
hardware	O
failure	O
in	O
the	O
middle	O
of	O
an	O
index	O
update	O
might	O
corrupt	O
the	O
index	O
.	O
</s>
<s>
VSAM	O
provides	O
an	O
ISAM	B-Application
/	O
VSAM	O
Interface	O
which	O
allows	O
ISAM-based	O
applications	O
to	O
use	O
VSAM	O
KSDS	O
without	O
reprogramming	O
.	O
</s>
<s>
Relative	O
Record	O
Datasets	O
(	O
RRDS	O
)	O
are	O
a	O
replacement	O
for	O
direct	O
access	O
(	O
BDAM	B-Application
)	O
datasets	O
,	O
allowing	O
applications	O
to	O
access	O
a	O
record	O
by	O
specifying	O
a	O
relative	O
record	O
number	O
.	O
</s>
<s>
These	O
VSAM	O
formats	O
became	O
the	O
basis	O
of	O
IBM	O
's	O
database	B-Application
management	I-Application
systems	I-Application
,	O
IMS/VS	B-Application
and	O
DB2	B-Application
-	O
usually	O
ESDS	O
for	O
the	O
actual	O
data	O
storage	O
and	O
KSDS	O
for	O
indexes	O
.	O
</s>
<s>
The	O
MVS	B-Application
Master	O
Catalog	O
must	O
be	O
a	O
VSAM	O
catalog	O
.	O
</s>
<s>
Catalogs	O
were	O
originally	O
provided	O
in	O
OS/360	B-Application
in	O
the	O
form	O
of	O
CVOLs	O
;	O
MVS	B-Application
added	O
a	O
separate	O
catalog	O
structure	O
for	O
VSAM	O
;	O
later	O
IBM	O
added	O
a	O
third	O
type	O
of	O
catalog	O
known	O
as	O
an	O
ICF	O
catalog	O
.	O
</s>
<s>
(	O
IBM	O
removed	O
support	O
for	O
CVOL	O
and	O
VSAM	O
catalogs	O
as	O
of	O
2000	O
,	O
since	O
they	O
were	O
not	O
Y2K-compliant	O
;	O
hence	O
in	O
z/OS	B-Application
,	O
only	O
ICF	O
catalogs	O
are	O
supported	O
.	O
)	O
</s>
<s>
In	O
1974	O
IBM	O
announced	O
Systems	B-Architecture
Network	I-Architecture
Architecture	I-Architecture
,	O
which	O
was	O
meant	O
to	O
reduce	O
the	O
cost	O
of	O
running	O
large	O
networks	O
of	O
terminals	O
,	O
mainly	O
by	O
using	O
communications	O
lines	O
much	O
more	O
efficiently	O
.	O
</s>
<s>
This	O
is	O
only	O
available	O
for	O
IBM	O
's	O
virtual	B-Architecture
memory	I-Architecture
operating	B-General_Concept
systems	I-General_Concept
,	O
since	O
its	O
mainframe	B-Architecture
software	O
component	O
,	O
VTAM	B-Application
is	O
only	O
available	O
with	O
these	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
1977	O
IBM	O
announced	O
MVS/System	O
Extensions	O
,	O
a	O
program	O
product	O
(	O
i.e.	O
,	O
it	O
cost	O
extra	O
money	O
)	O
which	O
improved	O
MVS	B-Application
performance	O
and	O
added	O
functionality	O
.	O
</s>
<s>
Descendants	O
of	O
MVS	B-Application
are	O
still	O
used	O
on	O
the	O
latest	O
descendants	O
of	O
System/360	B-Application
,	O
System/390	B-Device
and	O
zSeries	O
;	O
it	O
was	O
renamed	O
to	O
OS/390	B-Application
for	O
System/390	B-Device
,	O
and	O
the	O
64-bit	B-Device
version	O
for	O
the	O
zSeries	O
was	O
named	O
z/OS	B-Application
.	O
</s>
<s>
For	O
reasons	O
of	O
size	O
,	O
this	O
section	O
concentrates	O
on	O
the	O
MVT	O
option	O
of	O
OS/360	B-Application
;	O
PCP	O
and	O
MFT	O
are	O
very	O
similar	O
;	O
with	O
changes	O
in	O
nomenclature	O
and	O
some	O
minor	O
differences	O
.	O
</s>
<s>
OS/VS1	B-Application
and	O
SVS	B-Application
Have	O
much	O
the	O
same	O
structure	O
as	O
MFT	O
II	O
and	O
MVT	O
,	O
while	O
MVS	B-Application
,	O
although	O
retaining	O
much	O
of	O
the	O
logic	O
of	O
MVT	O
,	O
has	O
major	O
enhancements	O
better	O
addressed	O
in	O
a	O
separate	O
article	O
.	O
</s>
<s>
OS/360	B-Application
assigns	O
processors	O
to	O
tasks	O
,	O
which	O
are	O
analogous	O
to	O
light-weight	B-Operating_System
processes	I-Operating_System
or	O
threads	B-Operating_System
in	O
other	O
systems	O
.	O
</s>
<s>
Each	O
task	O
has	O
a	O
Task	B-Operating_System
Control	I-Operating_System
Block	I-Operating_System
(	O
TCB	O
)	O
and	O
a	O
stack	O
of	O
Request	O
Blocks	O
(	O
RBs	O
)	O
.	O
</s>
<s>
MVS	B-Application
assigns	O
processors	O
to	O
address	B-General_Concept
spaces	I-General_Concept
,	O
which	O
are	O
analogous	O
to	O
processes	O
,	O
and	O
to	O
Service	B-Application
Request	I-Application
Block	I-Application
(	O
SRBs	O
)	O
and	O
tasks	O
within	O
address	B-General_Concept
spaces	I-General_Concept
.	O
</s>
<s>
Each	O
address	O
space	O
has	O
an	O
Address	O
Space	O
Control	O
Block	O
(	O
ASCB	O
)	O
,	O
a	O
queue	B-Device
of	O
SRBs	O
and	O
a	O
queue	B-Device
of	O
TCBs	O
.	O
</s>
<s>
In	O
OS/360	B-Application
all	O
storage	O
is	O
visible	O
to	O
all	O
code	O
,	O
although	O
fetch	O
protection	O
may	O
prevent	O
access	O
by	O
unprivileged	O
code	O
to	O
some	O
control	O
blocks	O
or	O
between	O
jobs	O
.	O
</s>
<s>
System	O
Queue	B-Device
Area	O
(	O
SQA	O
)	O
.	O
</s>
<s>
Contains	O
a	O
swapped-in	O
TSO	B-Application
session	O
.	O
</s>
<s>
Created	O
by	O
the	O
Time	B-General_Concept
Sharing	I-General_Concept
Control	O
(	O
TSC	O
)	O
task	O
.	O
</s>
<s>
This	O
is	O
an	O
area	O
into	O
which	O
MVT	O
loads	O
reentrant	O
access	B-Application
method	I-Application
routines	O
and	O
other	O
programs	O
at	O
IPL	O
time	O
that	O
can	O
subsequently	O
be	O
shared	O
by	O
all	O
jobs	O
.	O
</s>
<s>
SVS	B-Application
is	O
similar	O
except	O
that	O
the	O
system	O
area	O
is	O
at	O
the	O
top	O
and	O
bottom	O
of	O
virtual	B-Architecture
storage	I-Architecture
rather	O
than	O
real	O
storage	O
,	O
the	O
Nucleus	O
is	O
in	O
Virtual	O
=	O
Real	O
(	O
V=	O
R	O
)	O
storage	O
,	O
the	O
private	O
area	O
contains	O
a	O
Local	O
System	O
Queue	B-Device
Area	O
(	O
LSQA	O
)	O
for	O
each	O
region	O
and	O
the	O
LPA	O
is	O
split	O
into	O
:	O
</s>
<s>
In	O
MVS	B-Application
all	O
address	B-General_Concept
spaces	I-General_Concept
share	O
the	O
system	O
area	O
but	O
not	O
the	O
private	O
area	O
.	O
</s>
<s>
MVS	B-Application
adds	O
:	O
</s>
<s>
This	O
is	O
an	O
area	O
from	O
which	O
MVS	B-Application
can	O
dynamically	O
allocate	O
storage	O
shared	O
by	O
all	O
address	B-General_Concept
spaces	I-General_Concept
.	O
</s>
<s>
This	O
is	O
an	O
area	O
containing	O
control	O
blocks	O
that	O
in	O
OS/360	B-Application
and	O
SVS	B-Application
had	O
been	O
contained	O
in	O
SYS1.SYSJOBQE	O
.	O
</s>
<s>
In	O
MVS/XA	O
and	O
later	O
,	O
there	O
are	O
system	O
,	O
private	O
and	O
common	O
areas	O
below	O
the	O
(	O
224	O
bytes	O
)	O
line	O
,	O
and	O
extended	O
areas	O
between	O
and	O
(	O
231	O
bytes	O
)	O
.	O
</s>
<s>
In	O
z/OS	B-Application
,	O
the	O
storage	O
layout	O
is	O
similar	O
to	O
that	O
of	O
MVS/XA	O
,	O
MVS/ESA	O
and	O
OS/390	B-Application
;	O
storage	O
above	O
the	O
bar	O
is	O
managed	O
by	O
different	O
services	O
than	O
storage	O
below	O
the	O
bar	O
.	O
</s>
<s>
However	O
,	O
as	O
it	O
initializes	O
various	O
OS	O
facilities	O
it	O
begins	O
using	O
standard	O
services	O
,	O
e.g.	O
,	O
it	O
uses	O
the	O
macro	O
to	O
read	O
a	O
Data	B-Application
Set	I-Application
Control	I-Application
Block	I-Application
(	O
DSCB	O
)	O
from	O
a	O
Volume	B-Application
Table	I-Application
of	I-Application
Contents	I-Application
(	O
VTOC	B-Application
)	O
.	O
</s>
<s>
In	O
addition	O
to	O
batch	B-General_Concept
jobs	I-General_Concept
,	O
OS/360	B-Application
supports	O
several	O
categories	O
of	O
work	O
that	O
it	O
handles	O
similarly	O
to	O
batch	B-General_Concept
jobs	I-General_Concept
.	O
</s>
<s>
In	O
all	O
cases	O
the	O
system	O
has	O
to	O
process	O
JCL	B-Application
,	O
allocate	O
a	O
region	O
,	O
allocate	O
devices	O
and	O
initiate	O
the	O
job-step	O
program	O
.	O
</s>
<s>
For	O
a	O
batch	B-General_Concept
job	I-General_Concept
,	O
the	O
Reader/Interpreter	O
processes	O
JCL	B-Application
from	O
an	O
external	O
device	O
;	O
for	O
commands	O
,	O
commands	O
and	O
TSO	B-Application
,	O
the	O
system	O
generates	O
JCL	B-Application
invoking	O
a	O
cataloged	O
procedure	O
.	O
</s>
<s>
OS/360	B-Application
has	O
a	O
control	O
block	O
known	O
as	O
the	O
Communications	O
Vector	O
Table	O
(	O
CVT	O
)	O
,	O
which	O
contains	O
pointers	O
to	O
other	O
control	O
blocks	O
and	O
to	O
various	O
routines	O
.	O
</s>
<s>
Some	O
of	O
the	O
OS/360	B-Application
macro-instructions	O
refer	O
to	O
fields	O
in	O
the	O
CVT	O
and	O
other	O
control	O
blocks	O
.	O
</s>
<s>
OS/360	B-Application
has	O
macros	O
to	O
provide	O
dsect	O
mappings	O
of	O
some	O
control	O
blocks	O
,	O
although	O
many	O
macros	O
have	O
hard	O
coded	O
offsets	O
rather	O
than	O
the	O
names	O
in	O
the	O
mapping	O
macros	O
.	O
</s>
<s>
OS/360	B-Application
services	O
typically	O
have	O
parameters	O
in	O
register	O
1	O
;	O
some	O
use	O
registers	O
0	O
and	O
1	O
and	O
some	O
use	O
registers	O
0	O
,	O
1	O
and	O
15	O
.	O
</s>
<s>
OS/360	B-Application
service	O
macros	O
often	O
have	O
three	O
forms	O
:	O
</s>
<s>
MCS	O
allows	O
recording	O
of	O
message	O
traffic	O
on	O
a	O
hardcopy	O
log	O
,	O
which	O
may	O
be	O
either	O
a	O
secondary	O
console	O
or	O
the	O
system	O
log	O
(	O
SYSLOG	O
)	O
on	O
DASD	B-Application
.	O
</s>
<s>
A	O
key	O
command	O
for	O
display	O
consoles	O
,	O
e.g.	O
,	O
2250	B-Device
,	O
2260	B-Device
,	O
3270	B-Operating_System
,	O
is	O
CONTROL	O
(	O
K	O
)	O
,	O
which	O
sets	O
processing	O
options	O
for	O
,	O
e.g.	O
,	O
scrolling	O
.	O
</s>
<s>
Announced	O
Shipped	O
Supportdropped	O
Rel	O
#	O
Name	O
360S	O
1964-04	O
Operating	B-Application
System/360	I-Application
1964-04	O
1965-11	O
1	O
Operating	B-Application
System/360	I-Application
prereleaseSingle	O
Sequential	O
Scheduler	O
1964-04	O
1966-11	O
OS/360	B-Application
Multiple	O
Sequential	O
Scheduler	O
360S	O
1965-12	O
1966-03-31	O
1	O
Operating	B-Application
System/360	I-Application
360S	O
1966-06	O
2	O
Operating	B-Application
System/360	I-Application
360S	O
1966-08-18	O
1966-08	O
4/5	O
Operating	B-Application
System/360	I-Application
360S	O
1966-04-29	O
1966-10	O
6	O
Operating	O
System/360MFT	O
360S	O
1966-12-07	O
8	O
Operating	B-Application
System/360	I-Application
360S	O
1967-02	O
9.5	O
Operating	B-Application
System/360	I-Application
360S	O
1967-05	O
11	O
Operating	B-Application
System/360	I-Application
360S	O
1967-08-08	O
12	O
Operating	O
System/360MVT	O
?	O
</s>
<s>
360S	O
1967-08	O
13	O
Operating	O
System/360MVT	O
360S	O
1968-01	O
14	O
Operating	B-Application
System/360	I-Application
360S	O
1968-08-30	O
15/16	O
Operating	O
System/360MFT	O
-II	O
,	O
VTOC	B-Application
positioning	O
360S	O
1969-03	O
17	O
Operating	B-Application
System/360	I-Application
360S	O
1969-07	O
1969-09	O
18	O
Operating	O
System/360SMF	O
for	O
MVT	O
360S	O
1969-10	O
18.6	O
Operating	B-Application
System/360	I-Application
360S	O
1970-03	O
19	O
Operating	B-Application
System/360	I-Application
360S	O
1970-06-01	O
1970-08-05	O
19.1	O
Operating	O
System/360SMF	O
for	O
MFT	O
,	O
MFT	O
Attach	O
,	O
1285/87/88	O
support	O
360S	O
1970-08-05	O
19.6	O
Operating	B-Application
System/360	I-Application
360S	O
1970-09	O
20	O
Operating	O
System/360xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1	O
360S	O
1971-02	O
20.1	O
Operating	B-Application
System/360	I-Application
360S	O
20.6	O
Operating	B-Application
System/360	I-Application
360S	O
21	O
Operating	B-Application
System/360	I-Application
360S	O
21.6	O
Operating	B-Application
System/360	I-Application
360S	O
21.7	O
Operating	B-Application
System/360	I-Application
360S	O
1972-08	O
21.8	O
Operating	B-Application
System/360	I-Application
5741	O
1972-08	O
1973-	O
??	O
</s>
<s>
1	O
Operating	O
System/Virtual	O
Storage	O
1	O
(	O
OS/VS1	B-Application
)	O
5742-SC1	O
1972-08	O
1972-	O
??	O
</s>
<s>
1	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
(	O
Single	O
Virtual	B-Architecture
Storage	I-Architecture
)	O
(	O
SVS	B-Application
)	O
5752-VS2	O
1972-08	O
1974-	O
??	O
</s>
<s>
2	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
(	O
Multiple	O
Virtual	B-General_Concept
address	I-General_Concept
Spaces	I-General_Concept
)	O
(	O
MVS	B-Application
)	O
with	O
Job	B-Application
Entry	I-Application
Subsystem	I-Application
2	O
(	O
JES2	B-Application
)	O
5752-VS2	O
1972-	O
??	O
</s>
<s>
1975-10	O
2	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystem	I-Application
3	I-Application
(	O
JES3	B-Application
)	O
5752-VS2	O
?	O
</s>
<s>
2.1	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystem	I-Application
3	I-Application
(	O
JES3	B-Application
)	O
5752-VS2	O
1975-	O
??	O
</s>
<s>
1975-10	O
3	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystems	I-Application
2	O
and	O
3	O
(	O
JES2	B-Application
and	O
JES3	B-Application
)	O
5752-VS2	O
?	O
</s>
<s>
3.6	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystems	I-Application
2	O
and	O
3	O
(	O
JES2	B-Application
and	O
JES3	B-Application
)	O
5752-VS2	O
1976-11	O
?	O
</s>
<s>
3.7	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystems	I-Application
2	O
and	O
3	O
(	O
JES2	B-Application
and	O
JES3	B-Application
)	O
5752-VS2	O
1979-	O
??	O
</s>
<s>
3.8	O
Operating	O
System/Virtual	O
Storage	O
2	O
(	O
OS/VS2	B-Application
)	O
MVS	B-Application
with	O
Job	B-Application
Entry	I-Application
Subsystems	I-Application
2	O
and	O
3	O
(	O
JES2	B-Application
and	O
JES3	B-Application
)	O
5740-XE1	O
1979-	O
??	O
</s>
<s>
1	O
MVS/System	O
Extensions	O
(	O
MVS/SE	O
)	O
5740-XE1	O
1979-03	O
1979-08	O
2	O
MVS/System	O
Extensions	O
(	O
MVS/SE2	O
)	O
5740-XYS	O
1980-06	O
1980-12	O
1	O
MVS/System	O
Product	O
Version	O
1	O
JES2	B-Application
(	O
MVS/SP	O
1.1	O
)	O
5740-XYN	O
1980-06	O
1980-12	O
1	O
MVS/System	O
Product	O
Version	O
1	O
JES3	B-Application
(	O
MVS/SP	O
1.1	O
)	O
5740-XYS	O
1980-06	O
1981-06	O
2	O
MVS/System	O
Product	O
Version	O
1	O
JES2	B-Application
(	O
MVS/SP	O
1.2	O
)	O
5740-XYN	O
1980-06	O
1981-06	O
2	O
MVS/System	O
Product	O
Version	O
1	O
JES3	B-Application
(	O
MVS/SP	O
1.2	O
)	O
5740-XYS	O
1980-11	O
1981-10	O
3	O
MVS/System	O
Product	O
Version	O
1	O
JES2	B-Application
(	O
MVS/SP	O
1.3	O
)	O
5740-XYN	O
1980-11	O
1981-10	O
3	O
MVS/System	O
Product	O
Version	O
1	O
JES3	B-Application
(	O
MVS/SP	O
1.3	O
)	O
5740-XC6	O
1981-10	O
1983-03	O
1	O
MVS/System	O
Product	O
-	O
JES2	B-Application
Version	O
2	O
(	O
MVS/Extended	O
Architecture	O
)	O
(	O
MVS/XA	O
)	O
5740-XC6	O
1981-10	O
1983-03	O
1	O
MVS/System	O
Product	O
-	O
JES3	B-Application
Version	O
2	O
(	O
MVS/Extended	O
Architecture	O
)	O
(	O
MVS/XA	O
)	O
5685-001	O
1988-02	O
1988-07	O
1	O
MVS/System	O
Product	O
-	O
JES2	B-Application
Version	O
3	O
(	O
MVS/Enterprise	O
System	O
Architecture	O
)	O
(	O
MVS/ESA	O
)	O
5685-002	O
1988-02	O
1988-07	O
1	O
MVS/System	O
Product	O
-	O
JES3	B-Application
Version	O
3	O
(	O
MVS/Enterprise	O
System	O
Architecture	O
)	O
(	O
MVS/ESA	O
)	O
5685-047	O
1990-09-05	O
1990-10-26	O
1994-03-31	O
1	O
MVS/ESA	O
SP	O
-	O
JES2	B-Application
Version	O
4	O
5685-047	O
1990-09-05	O
1992-12-31	O
1999-06-30	O
2	O
MVS/ESA	O
SP	O
-	O
JES2	B-Application
Version	O
4	O
5685-047	O
1992-06-18	O
1993-03-26	O
1999-06-30	O
3	O
MVS/ESA	O
SP	O
-	O
JES2	B-Application
Version	O
4	O
5685-048	O
1990-09	O
1990-10	O
1999-06-30	O
1	O
MVS/ESA	O
SP	O
-	O
JES3	B-Application
Version	O
4	O
5655-068	O
1994-04-05	O
1994-06-24	O
2001-01-31	O
1	O
MVS/ESA	O
SP	O
-	O
JES2	B-Application
Version	O
5	O
5655-068	O
1994-09-13295-072	O
1995-06-30	O
2001-03-31	O
2	O
MVS/ESA	O
SP	O
-	O
JES2	B-Application
Version	O
5	O
5655-069	O
1994-09-13	O
1995-29-13	O
2001-03-31	O
2.1	O
MVS/ESA	O
SP	O
-	O
JES3	B-Application
Version	O
5	O
5655-069	O
1995-02-28295-072	O
1995-09-29	O
2.2	O
MVS/ESA	O
SP	O
-	O
JES3	B-Application
Version	O
5	O
5645-001	O
1996-02-20	O
1996-03-29296-018	O
2001-01-31	O
1	O
OS/390	B-Application
Version	O
1	O
5645-001	O
1996-02-20296-018	O
1996-09-27	O
2001-01-31	O
2	O
OS/390	B-Application
Version	O
1	O
5645-001	O
1996-09-10	O
1997-03-11297-040	O
2001-03-31	O
3	O
OS/390	B-Application
Version	O
1	O
5647-A01	O
1997-03-11297-040	O
1997-09-26297-355	O
2001-03-31	O
4	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
1997-09-09297-355	O
1998-03-27297-355	O
2001-03-31298-049	O
5	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
1998-02-24298-049	O
1998-09-25298-278	O
2002-03-31	O
6	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
1998-08-18298-278	O
1999-03-26299-042	O
2002-03-31	O
7	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
1999-02-22299-042	O
1999-09-24299-234	O
2002-09-30	O
8	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
2000-02-29299-234	O
2000-03-31200-030	O
2003-03-31	O
9	O
OS/390	B-Application
Version	O
2	O
5647-A01	O
2000-05-16	O
2000-09-29200-145	O
2004-09-30	O
10	O
OS/390	B-Application
Version	O
2	O
5694-A01	O
2000-10-03200-352	O
2001-03-30	O
2004-03-31	O
1	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2001-09-11201-248	O
2001-10-26	O
2004-10-31	O
2	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2002-02-19202-031	O
2002-03-29	O
2005-03-31	O
3	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2002-08-13202-190	O
2002-09-27	O
2007-03-31	O
4	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2004-02-10	O
204-017	O
2004-03-26	O
2007-03-31	O
5	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2004-08-10204-180	O
2004-09-24	O
2007-09-30	O
6	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2005-07-27205-167	O
2005-09-30	O
2008-09-30	O
7	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2006-08-08206-190	O
2006-09-29	O
2009-09-30	O
8	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2007-08-08207-175	O
2007-09-28	O
2010-09-30	O
9	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2008-08-05208-186	O
2008-09-26	O
2011-09	O
10	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2009-08-18209-242	O
2009-09-25	O
2013-09	O
11	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2010-07-22210-235	O
2010-09-24	O
2015-09	O
12	O
z/OS	B-Application
Version	O
1	O
5694-A01	O
2011-07-12211-252	O
2011-09-30	O
2017-09	O
13	O
z/OS	B-Application
Version	O
1	O
5650-ZOS	O
2013-07-23213-292	O
2013-09-30	O
2019-09	O
z/OS	B-Application
Version	O
2	O
5650-ZOS	O
2015-07-28215-267	O
2015-09-30	O
2021-09	O
z/OS	B-Application
Version	O
2	O
5650-ZOS	O
2017-07-17217-246	O
2017-09-27	O
2022-09-30	O
z/OS	B-Application
Version	O
2	O
5650-ZOS	O
2019-02-26219-013	O
2019-09-30	O
z/OS	B-Application
Version	O
2	O
5650-ZOS	O
2021-06-27221-260	O
2021-09-30	O
z/OS	B-Application
Version	O
2	O
z/OS	B-Application
Version	O
3	O
Order	O
No	O
.	O
</s>
