<s>
Time	B-Application
Sharing	I-Application
Option	I-Application
(	O
TSO	O
)	O
is	O
an	O
interactive	O
time-sharing	B-General_Concept
environment	O
for	O
IBM	B-Device
mainframe	I-Device
operating	O
systems	O
,	O
including	O
OS/360	O
MVT	O
,	O
OS/VS2	B-Application
(	O
SVS	O
)	O
,	O
MVS	B-Application
,	O
OS/390	B-Application
,	O
and	O
z/OS	B-Application
.	O
</s>
<s>
In	O
computing	O
,	O
time-sharing	B-General_Concept
is	O
a	O
design	O
technique	O
that	O
allows	O
many	O
people	O
to	O
use	O
a	O
computer	O
system	O
concurrently	O
and	O
independently	O
—	O
without	O
interfering	O
with	O
each	O
other	O
.	O
</s>
<s>
TSO	O
is	O
most	O
commonly	O
used	O
by	O
mainframe	O
system	B-Application
administrators	I-Application
and	O
programmers	O
.	O
</s>
<s>
But	O
most	O
mainframe	O
interaction	O
is	O
actually	O
via	O
ISPF	B-Operating_System
,	O
which	O
allows	O
for	O
customized	O
menu-driven	O
interaction	O
.	O
</s>
<s>
This	O
combination	O
is	O
called	O
TSO/ISPF	O
.	O
</s>
<s>
TSO	O
can	O
also	O
provide	O
a	O
Unix-style	O
environment	O
on	O
OS/390	B-Application
and	O
z/OS	B-Application
via	O
the	O
UNIX	B-Operating_System
System	I-Operating_System
Services	I-Operating_System
command	B-Application
shell	I-Application
,	O
with	O
or	O
without	O
ISPF	B-Operating_System
.	O
</s>
<s>
TSO	O
commands	O
can	O
be	O
embedded	O
in	O
REXX	B-Language
execs	O
or	O
CLISTs	B-Operating_System
,	O
which	O
can	O
run	O
interactively	O
or	O
in	O
batch	O
.	O
</s>
<s>
TSO	O
eliminated	O
the	O
need	O
to	O
punch	B-Architecture
cards	I-Architecture
on	O
a	O
keypunch	B-Device
machine	I-Device
,	O
and	O
send	O
card	B-Architecture
decks	I-Architecture
to	O
the	O
computer	O
room	O
to	O
be	O
read	O
by	O
a	O
card	B-Device
reading	I-Device
machine	O
.	O
</s>
<s>
When	O
it	O
was	O
originally	O
introduced	O
in	O
1971	O
,	O
IBM	O
considered	O
time-sharing	B-General_Concept
an	O
"	O
optional	O
feature	O
"	O
,	O
as	O
compared	O
to	O
standard	O
batch	B-General_Concept
processing	I-General_Concept
,	O
and	O
hence	O
offered	O
TSO	O
as	O
an	O
option	O
for	O
OS/360	O
MVT	O
.	O
</s>
<s>
With	O
the	O
introduction	O
of	O
MVS	B-Application
in	O
1974	O
,	O
IBM	O
made	O
it	O
a	O
standard	O
component	O
of	O
their	O
top-end	O
mainframe	O
operating	O
system	O
.	O
</s>
<s>
TSO/E	O
is	O
a	O
base	O
element	O
of	O
z/OS	B-Application
.	O
</s>
<s>
Before	O
z/OS	B-Application
,	O
TSO	O
Extensions	O
(	O
TSO/E	O
)	O
was	O
an	O
element	O
of	O
OS/390	B-Application
and	O
was	O
a	O
licensed	O
program	O
for	O
the	O
MVS	B-Application
and	O
MVS/ESA	O
System	O
Products	O
.	O
</s>
<s>
Since	O
all	O
z/OS	B-Application
installations	O
usually	O
have	O
both	O
TSO	O
and	O
TSO/E	O
functions	O
installed	O
,	O
it	O
is	O
normal	O
to	O
refer	O
to	O
both	O
TSO	O
and	O
TSO/E	O
as	O
"	O
TSO	O
"	O
.	O
</s>
<s>
It	O
is	O
common	O
to	O
run	O
TSO	O
in	O
batch	O
(	O
as	O
opposed	O
to	O
interactively	O
)	O
:	O
all	O
the	O
usual	O
TSO	O
line-mode	O
interactive	O
commands	O
can	O
be	O
also	O
executed	O
via	O
Job	B-Application
Control	I-Application
Language	I-Application
(	O
JCL	O
)	O
by	O
running	O
any	O
of	O
the	O
programs	O
IKJEFT01	O
,	O
IKJEFT1A	O
,	O
and	O
IKJEFT1B	O
and	O
supplying	O
the	O
line	O
commands	O
in	O
a	O
file	O
pointed	O
to	O
by	O
the	O
SYSTSIN	O
DD	O
.	O
</s>
<s>
Batch	O
execution	O
of	O
TSO	O
is	O
one	O
way	O
to	O
allow	O
an	O
IBM	B-Device
mainframe	I-Device
application	O
to	O
access	O
DB2	B-Application
resources	O
.	O
</s>
