CLIST (original) (raw)

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Programming language

CLIST (Command List) (pronounced "C-List") is a procedural programming language for TSO in MVS systems. It originated in OS/360[1] Release 20 and has assumed a secondary role since the availability of Rexx in TSO/E Version 2. In its basic form, a CLIST program is a list of commands to be executed in strict sequence (like a DOS batch file (*.bat) file). OS/VS2 R3.6 (MVS) added If-Then-Else logic and loop constructs to CLIST.[2] The term CLIST is also used for command lists written by users of NetView.[3]

CLIST is an interpreted language. 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. (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, for example). CLISTs can be run in background[ii][iii]. CLISTs can display TSO I/O screens and menus by using ISPF dialog services.

Compare the function of CLIST with that provided by REXX.

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

  1. ^ Usually IKJEFT01

  2. ^ by running JCL that executes a TSO terminal monitor program[i] (TMP)

  3. ^ This capability was added by the program product Time Sharing Option/Extensions (TSO/E), which is a standard part of OS/390 and z/OS.

  4. ^ "Command Procedure Statements" (PDF). IBM System/360 Operating System: Time Sharing Option - Command Language Reference (PDF). Systems Reference Library (Fifth ed.). IBM. April 1973. pp. 245–249. GC28-6732-3. Retrieved September 29, 2025.

  5. ^ "Command Procedure" (PDF). OS/VS2 TSO - Command Language Reference (PDF). Systems (Fourth ed.). IBM. January 1976. pp. 271–324. GC28-0646-3. Retrieved September 29, 2025.

  6. ^ "z/OS TSO/E CLISTs". z/OS 2.1.0. IBM. 14 June 2013. Retrieved 12 May 2016.