PL/I considerations

User condition handlers can now be written in PL/I; that is, you can register a PL/I external procedure as a user-written condition handler using the Language Environment callable service CEEHDLR, and unregister it using CEEHDLU.

Restrictions on PL/I user-written condition handlers are:
  • If a user handler is registered in the PL/I main routine, it must be unregistered using CEEHDLU before the main returns via a RETURN statement or by reaching the END statement. One implication is that a user handler registered in the main routine does not gain control for the PL/I FINISH condition raised due to normal termination of the main routine.
  • You cannot collapse multiple BEGIN blocks using a RETURN statement when CEEHDLR has been invoked within a nested block.
  • The following condition handling pseudovariables and built-in functions are still restricted to PL/I ON-units and are not available in user handlers:
    • DATAFIELD
    • ONCHAR
    • ONCODE
    • ONCOUNT
    • ONFILE
    • ONKEY
    • ONLOC
    • ONSOURCE
  • User-written condition handlers are not supported in PL/I multitasking applications.
Parent topic: Coding a user-written condition handler