Writing REXX Execs

Restructured extended executor (REXX) is a high-level interpretive language that enables you to write programs in a clear and structured way. You can write programs in the REXX language, called execs, that perform given tasks or groups of tasks.

REXX execs have many characteristics that are similar to CLISTs. For example, using either the REXX or CLIST language, you can:

Perform numerous tasks, including issuing multiple TSO/E commands and invoking programs written in other languages.
Write structured programs, perform I/O and process arithmetic and character data.
Write interactive applications by issuing commands of ISPF to display full-screen panels.
Provide easy-to-use interfaces to applications written in other languages. Execs can prompt the terminal user for information on the tasks the user requests, set up the environment needed for the application, and then issue the commands needed to invoke the application program.

However, a significant difference between execs and CLISTs is that you can execute CLISTs only in a TSO/E environment. REXX execs do not require a TSO/E environment, and can execute in any MVS™ address space. In addition, you can use the Systems Application Architecture® (SAA) Procedures Language to write execs that are system independent. The SAA Procedures Language, which is a subset of the REXX language, enables you to write execs to run in multiple host environments.

TSO/E Release 3 extended the REXX language to provide host environments that support the common programming interface (CPI) and LU 6.2-based APPC/MVS callable services. Using these host environments, you can write a REXX exec to act as an APPC/MVS transaction program or communicate with other APPC/MVS transaction programs. Because these transaction programs can be used across different machines, greater system connectivity is possible.

For information on writing and executing execs, see z/OS TSO/E User's Guide and z/OS TSO/E REXX Reference.