Calling another REXX program as a command

You can call another program as an external routine, or you can call a program from another program explicitly with the EXEC command.

Subroutines and functions discussed how to call another program as an external routine. You can also call a program from another program explicitly with the EXEC command. Like an external routine, a program called explicitly or implicitly can return a value to the caller with the RETURN or EXIT instruction. Unlike an external routine, which passes a value to the special variable RESULT, the program that is called passes a value to the REXX special variable RC.

To explicitly call another program from within a program, use the EXEC command as you would any other REXX/CICS command. The called program should end with a RETURN or EXIT instruction, ensuring that control returns to the caller. The REXX special variable RC is set to the return code from the EXEC command. You can optionally return a value to the caller on the RETURN or EXIT instruction. When control passes back to the caller, the REXX special variable RC is set to the value of the expression returned on the RETURN or EXIT instruction.

For example, to call a program named CALC and pass it an argument of four numbers, you could include the following instructions:

"EXEC calc 24 55 12 38"
SAY 'The result is' RC

CALC might contain the following instructions:

ARG number1 number2 number3 number4
answer = number1 * (number2 + number3) - number4
RETURN answer