Processing Considerations

Consider the following when writing an event exit routine:

The event exit routine must be a reentrant program.
If a connection can perform required processing for an event synchronously in the event exit (that is, the user can respond to the event at the time it occurs), exit processing should not be long-running and should not suspend the event exit SRB. As long as the event exit is running, the connection cannot receive information about other events as they occur because XES serializes its invocations of the event exit on a connection basis.
It is advisable to check the connection level of the subject of the event. If you are in an environment with connectors of mixed connection levels, it is possible that you might be notified of an event that your event exit has not provided for (because you are processing at a “lower level” of MVS™). If that situation occurs, you should set the EEPLRETCODE to X'00' and return to MVS, rather than to treat the unknown or unexpected event as an error.