CLIST (Command List) (pronounced "C-List") is a
procedural programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
for
TSO in
MVS systems. It originated in
OS/360
OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB ...
Release 20 and has assumed a secondary role since the availability of
Rexx in TSO/E Version 2. The term CLIST is also used for command lists written by users of
NetView.
In its basic form, a CLIST program (or "CLIST" for short) can take the form of a simple list of
commands to be executed in strict sequence (like a
DOS
DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems.
DOS may also refer to:
Computing
* Data over signalling (DoS), multiplexing data onto a signalling channel
* Denial-of-service attack (DoS), an attack on a communicat ...
batch file
Batch may refer to:
Food and drink
* Batch (alcohol), an alcoholic fruit beverage
* Batch loaf, a type of bread popular in Ireland
* A dialect term for a bread roll used in North Warwickshire, Nuneaton and Coventry, as well as on the Wirra ...
(*.bat) file). However, CLIST also features If-Then-Else logic as well as loop constructs.
CLIST is an
interpreted language
In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interprete ...
. That is, the computer must translate a CLIST every time the program is executed. CLISTs therefore tend to be slower than programs written in
compiled languages such as
COBOL,
FORTRAN, or
PL/1
PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. I ...
. (A program written in a compiled language is translated once to create a "load module" or
executable.)
CLIST can read/write MVS files and read/write from/to a TSO terminal. It can read parameters from the caller and also features a function to hold global variables and pass them between CLISTs. A CLIST can also call an MVS application program (written in
COBOL or
PL/I
PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. I ...
, for example). CLISTs can be run in background (by running
JCL which executes the TSO control program (IKJEFT01)). TSO I/O screens and menus using
ISPF
In computing, Interactive System Productivity Facility (ISPF) is a software product for many historic IBM mainframe operating systems and currently the z/OS and z/VM operating systems that run on IBM mainframes. It includes a screen editor, th ...
dialog services can be displayed by CLISTs.
Compare the function of CLIST with that provided by
REXX.
Example programs
PROC 0
WRITE HELLO WORLD!
Adding If-Then-Else logic:
/********************************************************************/
/* MULTI-LINGUAL "HELLO WORLD" PROGRAM. */
/* */
/* THIS CLIST, STORED AS USERID.TSO.CLIST(TEST), CAN BE INVOKED */
/* FROM THE ISPF COMMAND LINE AS SHOWN IN THE FOLLOWING EXAMPLE: */
/* */
/* COMMAND > TSO TEST SPANISH */
/* */
/********************************************************************/
PROC 1 LANGUAGE
IF &LANGUAGE = SPANISH THEN +
WRITE HOLA, MUNDO
ELSE IF &LANGUAGE = FRENCH THEN +
WRITE BONJOUR, MONDE
ELSE +
WRITE HELLO, WORLD
EXIT
See also
*
Rexx
Footnotes
References
IBM mainframe operating systems
Procedural programming languages
Command shells
Text-oriented programming languages
Scripting languages
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