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.
"EXEC calc 24 55 12 38"
SAY 'The result is' RC
ARG number1 number2 number3 number4
answer = number1 * (number2 + number3) - number4
RETURN answer