Programming Considerations

Consider the following when writing your status user routine:

To cause XCF to schedule the group user routines of the other active members, the status user routine must set a return code equal to the value in SEPLSTCH.
Because the status user routine runs in SRB mode, it cannot issue any SVCs. You might want to queue work to one or more tasks for processing and post the tasks when needed.
The member can pass data to its status user routine in the member data field (MEMDATA parameter on IXCJOIN). This data might be a pointer to some type of communication area, such as a control structure or an ECB. XCF passes member data to the status user routine as part of the parameter list (SEPLMDAT field).
When XCF is checking for status update missing, XCF will infer the status update missing condition if the status user routine does not complete in time. For example, if the status user routine tries to do recovery for the member, the routine might take too long trying to repair control structures or take a dump. For this reason, you should limit processing in the status user routine. (When XCF is checking for status update resumed, XCF does not make this assumption, so the status user routine can take longer.)