Programming considerations

Before this exit is invoked, the system does validity and authorization checking of the node and userid that is to receive the message. Therefore, if the exit changes the node or userid to which the message will be sent, the installation must check the validity and the authority of the new destination.
If errors were detected by the SSI service, the bit setting X042CANC will be on in the response byte, indicating that the notify message is to be canceled. If your exit routine corrects the error and turns X042CANC off, to issue the message, it should also zero out the exit-supplied reason and return codes in fields X042REAS and X042RC of the parameter list.
As the notify user SSI caller can be unauthorized, you must take special consideration if the SSNU extension is directly referenced in the exit routine. The SSI caller's key is provided so that the exit can reference SSNU data appropriately. Additionally, the $XPL contains fields so that the exit can update the userid, message text, and message length.
Note: IBM® suggests updating information in the XPL instead of the SSNU. When using the XPL fields, JES2 ensures the changes are appropriately handled. However, when changing the SSNU directly, the exit must understand how JES2 uses the SSNU fields in subsequent logic.