IRX

Enhanced Definition

`IRX` is the program name for the REXX interpreter in z/OS, serving as the primary entry point for executing REXX (Restructured Extended Executor) execs. When invoked, `IRX` loads and interprets a specified REXX program, providing the runtime environment for its execution within various z/OS contexts like TSO, batch, or ISPF.

Key Characteristics

- IRX is an executable program (load module) residing in a system library (e.g., SYS1.LINKLIB), not merely an internal command.
- It provides the runtime environment for REXX execs, managing variable scope, function calls, and external command processing.
- IRX can be invoked from TSO command lines, JCL batch jobs, or programmatically via callable services (IRXEXEC, IRXJCL).
- It supports the execution of REXX execs stored in PDS/PDSE members (typically with member type EXEC or REXX) or sequential datasets.
- The IRX program handles the parsing, tokenization, and interpretation of REXX statements, translating them into executable machine instructions.
- It manages the search order for REXX execs using SYSEXEC and SYSPROC DD statements, or the TSO/E ALLOC command.

Use Cases

- Interactive Execution in TSO: Running a REXX exec directly from the TSO READY prompt or within a TSO session, e.g., TSO IRX MYEXEC 'ARG1 ARG2'.
- Batch Job Processing: Invoking a REXX exec as a step in a JCL job stream to automate tasks, manipulate data, or perform system utility functions.
```
jcl
//STEP1 EXEC PGM=IRX,PARM='MYBATCHX PARM1'
//SYSEXEC DD DSN=MY.REXX.LIB,DISP=SHR
//SYSTSPRT DD SYSOUT=*
```
- ISPF Application Development: Using REXX execs as backend logic for ISPF panels, commands, or file tailoring, providing dynamic user interfaces and automation.
- System Automation and Monitoring: Developing REXX execs to monitor system events, automate operational tasks, or interact with system services like SDSF or NetView.
- Utility and Data Manipulation: Writing REXX scripts to process sequential