CA Global SubSystem › REXX Language in CA-GSS

REXX Language in CA-GSS

Note: CA‑GSS supplies extended functions for you to use when writing IMODs. For information about these functions, see the Reference Guide.

A REXX program is built from a series of instructions, commands, and function calls:

Instruction

Contains one or more clauses. In many instructions, the first clause starts with a keyword that identifies the instruction. Some instructions affect the flow of control, while other instructions provide services to the programmer. Some instructions, such as DO, include nested instructions.

Function

Is a built‑in subroutine that processes data and returns a value to the IMOD.

Command

Is any text string that is not an instruction, function, or operand. Commands are passed to the current environment for evaluation and disposition. The environment is determined by the program using the ADDRESS instruction and can be any of several non‑REXX programs. For example, commands can be passed to the CA Jobtrac Job Management environment for processing as CA Jobtrac Job Management commands.

CA‑GSS supports all REXX instructions, commands, and functions, with the following exceptions:

• The INTERPRET command is not supported.
• Labels cannot be duplicated.
• Function names and labels to be called are limited to 32 characters.

The REXX language uses the following conventions:

• Variables—Under REXX, all manipulated information must be stored as character strings in variables.
• Argument strings—When a REXX program or subroutine is invoked, one or more text strings can be passed to it as argument strings. How these strings are subdivided or parsed is up to the programmer.
• Result string—After a REXX program completed, it can pass a character string (result) back to the calling program.
• Program stack—The stack is a sequential collection of records of any content or length that is passed to a REXX program from an external source. This external source can either invoke the REXX program or be a program invoked from REXX. For this reason, the stack is sometimes referred to as the external data queue (EDQ). The REXX program can itself use the stack for working storage, although data must be moved to variables before most manipulations.

  Commands processed by external environments frequently accept and return data on the stack.

• Internal subroutines—A REXX program can contain subroutines. Such subroutines can access variables that belong to the calling routine. Internal subroutines are always compiled with the main routine, and are considered a part of the main routine.
• External subroutines—A REXX program can issue calls to external subroutines. External subroutines are separate from the routine that issues the call. An external subroutine does not share any variables with its caller except for global variables. The only values that can be passed are arguments, a result string, and the stack.