An exit routine must use synchronization services appropriate to its calling environment.

An exit routine called from the JES2 main task must use the JES2 $WAIT macro to wait for a JES2 event, resource, or post of a MVS™ ECB. An exit routine called from a JES2 subtask or from the user environment must use the MVS WAIT macro to wait for a system event. An exit routine called from a functional subsystem must also use MVS WAIT; $WAIT and $POST are not valid in this environment.

A JES2 main task exit routine should not invoke operating system services which may wait (WAIT), either voluntarily or involuntarily. Be aware of any product that interfaces with JES2 and attempts to issue MVS services such as STIMER, STIMERM, WAIT, or TTIMER under the JES2 main task, or which invoke MVS services such as allocation, which may issue such macros. An MVS wait from a JES2 main task exit routine would stop all of the JES2 main task processors, including any devices—such as readers, printers, and remote terminals—under their control.