Exception class data

Exception class monitoring data is information on CICS® resource shortages that are suffered by a transaction, such as queuing for file strings, or waiting for temporary storage. This data highlights possible problems in CICS system operation, and is intended to help you identify system constraints that affect the performance of your transactions. CICS writes one exception record for each exception condition that occurs.

Exception records are produced for each of the following resource shortages:
  • Wait for storage in the CDSA
  • Wait for storage in the UDSA
  • Wait for storage in the SDSA
  • Wait for storage in the RDSA
  • Wait for storage in the ECDSA
  • Wait for storage in the EUDSA
  • Wait for storage in the ESDSA
  • Wait for storage in the ERDSA
  • Wait for storage in the GCDSA
  • Wait for auxiliary temporary storage
  • Wait for auxiliary temporary storage string
  • Wait for auxiliary temporary storage buffer
  • Wait for auxiliary temporary storage write buffer
  • Wait for temporary storage queue
  • Wait for temporary storage data set extension
  • Wait for shared temporary storage
  • Wait for shared temporary storage pool
  • Wait for coupling facility data tables locking (request) slot
  • Wait for coupling facility data tables non-locking (request) slot (With coupling facility data tables each CICS has a number of slots available for requests in the CF data table. When all available slots are in use, any further request must wait.)
  • Wait for file buffer
  • Wait for LSRPOOL string
  • Wait for file string

Exception records are also produced when a policy threshold is exceeded.

An exception record is created each time any of the resources covered by exception class monitoring becomes constrained by system bottlenecks or a policy threshold is exceeded. The exception records are produced and written to SMF as soon as the resource shortage encountered by the transaction has been resolved or the policy threshold has been exceeded.

If performance class monitoring data is also being recorded, the performance class record for the transaction includes the total elapsed time the transaction was delayed by CICS system resource shortages, and a count of the number of exception records that have occurred for the task. The exception class records can be linked to the performance class records by either the transaction sequence number or the network unit-of-work ID.

You can enable exception class monitoring by coding MNEXC=ON (together with MN=ON) as a system initialization parameter. Alternatively you can use the monitoring facility transaction CEMN, or the CEMT or EXEC CICS SET MONITOR command, to enable exception class monitoring dynamically.