Establishing and deleting the signal interface routine

The syscalls('SIGON') function establishes the signal interface routine (SIR). After you establish the SIR, use the sigaction syscall command to catch the signals you want to process and the sigprocmask syscall command to unblock those signals.

Note: For a REXX program run from a z/OS shell or from a program, the SIR is established by default.

The syscalls('SIGON') function has these return values:

0: Successful completion.
4: The SIR could not be established. The usual cause for this is that another SIR has already been established for the process.

If you are writing a REXX program that runs a program that requires a signal interface routine (for example, a program that uses the C runtime library), you must delete the SIR. The syscalls('SIGOFF') function deletes the SIR and uses sigprocmask() to reset the signal process mask so that it blocks all signals that can be blocked.

The syscalls('SIGOFF') function has two return values:

0: Successful completion.
4: The SIR could not be deleted. The usual cause for this is that a SIR did not exist for the process.