How are CLISTs and REXX used?

The CLIST and REXX™ command languages shell script-type processing for TSO users.

With native TSO, it is possible to place a list of commands, called a command list or CLIST (pronounced "see list") in a file, and execute the list as if it were one command. When you invoke a CLIST, it issues the TSO/E commands in sequence. CLISTs are used for performing routine tasks; they enable users to work more efficiently with TSO.

For example, suppose that a file called AREA.COMMND contained the following sort commands:

ALLOCATE DATASET(AREA.CODES) FILE(SORTIN)    SHR
ALLOCATE DATASET(*)          FILE(SORTOUT)   SHR
ALLOCATE DATASET(*)          FILE(SYSOUT)    SHR
ALLOCATE DATASET(*)          FILE(SYSPRINT)  SHR
ALLOCATE DATASET(SORT.CNTL)  FILE(SYSIN)     SHR
CALL `SYS1.SICELINK(SORT)'

Instead of issuing each command individually, the user can achieve the same results by using just a single command to execute the CLIST, as follows:

EXEC 'CLIST AREA.COMMND'

TSO users create CLISTs with the CLIST command language. Another command language used with TSO is called Restructured Extended Executor or REXX. Both CLIST and REXX offer shell script-type processing. These command languages are interpretive languages, as opposed to compiled languages (although REXX can be compiled as well).

Some TSO users write functions directly as CLISTs or REXX programs, but these are more commonly implemented as ISPF functions, or by various software products. CLIST programming is unique to z/OS®, while the REXX language is used on many platforms.