The S502 abend indicates that the EVENTS table is too small.
The CA-GSS dispatcher is constructed around the z/OS EVENTS facility.
The EVENTS table must allow a slot for each pending (unprocessed) event.
Depending on dispatching priorities and selected options, the EVENTS table needs room to buffer deferred work.
An S502 abend usually indicates an EVENTS table that is too small, you have to increase the EVENTS value in your RUNPARM member.