Why is there a symptom dump for GSS STC and a S502 abend?

Products

• COMMON SERVICES FOR Z/OS

Issue/Introduction

A symptom dump has been produced for the GSS STC.           

There is an Abend S502 in GSS STC output:

IEA995I SYMPTOM DUMP OUTPUT                                                     
SYSTEM COMPLETION CODE=502  REASON CODE=00000000                                
 TIME=22.12.56  SEQ=04925  CPU=4000  ASID=0115                                  
 PSW AT TIME OF ERROR  070C1000   81579A08  ILC 2  INTC 0D                      
   NO ACTIVE MODULE FOUND                                                       
   NAME=UNKNOWN                                                                 
   DATA AT PSW  01579A02 - 00181610  0A0D9103  0950A7E4                         
   GR 0: 84000000   1: 84502000                                                 
      2: 00000000   3: 00000B80                                                 
      4: 009CDE88   5: 00000BD8                                                 
      6: 2657C268   7: 00F4FA00                                                 
      8: 0157AFE8   9: 00000000                                                 
      A: 7F53E290   B: 7FFFB918                                                 
      C: 00000BE0   D: 2658FF00                                                 
      E: 00FE9D00   F: 00000000                                                 
 END OF SYMPTOM DUMP                                                            
JOB GSS           STEP GSS1         
COMPLETION CODE      SYSTEM = 502      REASON CODE = 00000000                  

How this Abend S502 in GSS can be fixed?. 

Environment

Common Services 15.0

Resolution

The S502 abend indicates that the EVENTS table is too small.

The 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. 

The EVENTS value is used to determine how many separate internal processes can take place for IMODs in SYSVIEW for DB2. The EVENTS table is allocated in GSS stated task region and it is a reusable table that cycles so that it can appear to be larger than it is. Once a slot is vacated it is available for use when needed. It works in a circle and using the slots that have not been used sequentially until it finds one that has been used but not used currently.  
                                                                            
When the EVENTS table is exhausted GSS is not smart enough to getmain an additional set of tables. So when the EVENTS table get overflowed due to a high activity in IMODs you will get the Abend S502. The Max value for the EVENTS parameter is 32767. If you will not use all the slots then it is not necessary to increase to this value but I have found some of our customer works with the Max value without problem. 

The EVENTS value has to be increased in the RUNPARM member. 

Additional Information

You can check the Common Services 15.0 documentation for additional information:

EVENTS