<s>
CLIST	B-Operating_System
(	O
Command	O
List	O
)	O
(	O
pronounced	O
"	O
C-List	O
"	O
)	O
is	O
a	O
procedural	B-Application
programming	I-Application
language	I-Application
for	O
TSO	B-Application
in	O
MVS	B-Application
systems	O
.	O
</s>
<s>
It	O
originated	O
in	O
OS/360	B-Application
Release	O
20	O
and	O
has	O
assumed	O
a	O
secondary	O
role	O
since	O
the	O
availability	O
of	O
Rexx	B-Language
in	O
TSO/E	O
Version	O
2	O
.	O
</s>
<s>
The	O
term	O
CLIST	B-Operating_System
is	O
also	O
used	O
for	O
command	O
lists	O
written	O
by	O
users	O
of	O
NetView	O
.	O
</s>
<s>
In	O
its	O
basic	O
form	O
,	O
a	O
CLIST	B-Operating_System
program	O
(	O
or	O
"	O
CLIST	B-Operating_System
"	O
for	O
short	O
)	O
can	O
take	O
the	O
form	O
of	O
a	O
simple	O
list	O
of	O
commands	B-Application
to	O
be	O
executed	O
in	O
strict	O
sequence	O
(	O
like	O
a	O
DOS	B-Device
batch	O
file	O
( *	O
.bat	O
)	O
file	O
)	O
.	O
</s>
<s>
However	O
,	O
CLIST	B-Operating_System
also	O
features	O
If-Then-Else	O
logic	O
as	O
well	O
as	O
loop	O
constructs	O
.	O
</s>
<s>
CLIST	B-Operating_System
is	O
an	O
interpreted	B-Application
language	I-Application
.	O
</s>
<s>
That	O
is	O
,	O
the	O
computer	O
must	O
translate	O
a	O
CLIST	B-Operating_System
every	O
time	O
the	O
program	O
is	O
executed	O
.	O
</s>
<s>
CLISTs	B-Operating_System
therefore	O
tend	O
to	O
be	O
slower	O
than	O
programs	O
written	O
in	O
compiled	B-Language
languages	I-Language
such	O
as	O
COBOL	B-Application
,	O
FORTRAN	B-Application
,	O
or	O
PL/1	B-Language
.	O
</s>
<s>
(	O
A	O
program	O
written	O
in	O
a	O
compiled	B-Language
language	I-Language
is	O
translated	O
once	O
to	O
create	O
a	O
"	O
load	O
module	O
"	O
or	O
executable	B-Application
.	O
)	O
</s>
<s>
CLIST	B-Operating_System
can	O
read/write	O
MVS	B-Application
files	O
and	O
read/write	O
from/to	O
a	O
TSO	B-Application
terminal	O
.	O
</s>
<s>
It	O
can	O
read	O
parameters	O
from	O
the	O
caller	O
and	O
also	O
features	O
a	O
function	O
to	O
hold	O
global	O
variables	O
and	O
pass	O
them	O
between	O
CLISTs	B-Operating_System
.	O
</s>
<s>
A	O
CLIST	B-Operating_System
can	O
also	O
call	O
an	O
MVS	B-Application
application	O
program	O
(	O
written	O
in	O
COBOL	B-Application
or	O
PL/I	B-Language
,	O
for	O
example	O
)	O
.	O
</s>
<s>
CLISTs	B-Operating_System
can	O
be	O
run	O
in	O
background	O
(	O
by	O
running	O
JCL	B-Application
which	O
executes	O
the	O
TSO	B-Application
control	O
program	O
(	O
IKJEFT01	O
)	O
)	O
.	O
</s>
<s>
TSO	B-Application
I/O	O
screens	O
and	O
menus	O
using	O
ISPF	B-Operating_System
dialog	O
services	O
can	O
be	O
displayed	O
by	O
CLISTs	B-Operating_System
.	O
</s>
<s>
Compare	O
the	O
function	O
of	O
CLIST	B-Operating_System
with	O
that	O
provided	O
by	O
REXX	B-Language
.	O
</s>
