Troubleshooting SOS

New tasks can obtain an application server even when the system is short on storage (SOS). In this condition, tasks run, but with degraded performance.

When the SOS condition occurs, CICS® sends one or other of these messages to the console.nnnnnn file: 
ERZ048001I CICS Is Under Stress - Short on Task Shared storage.
ERZ048002I CICS Is Under Stress - Short on Runtime Support storage.

If you see a repeating pattern of messages telling you that CICS is short on storage, then it is not short on storage, a transaction might well contain a GETMAIN/FREEMAIN loop.

If you cannot see any SOS messages in the console.nnnnnn file, you can find out how many times CICS has raised SOS from the storage statistics.

Note:
  1. CICS also raises the SOS condition if a task makes an unconditional request for storage when the system is approaching SOS. If the request is for task shared storage, CICS suspends the task that is making the unconditional request.
  2. Short-on-storage messages might mean only that a greater volume of work than normal is running through your system. It could also be that the nature of transactions has changed, putting increased demands on a particular pool. Both these conditions can be resolved by increasing the appropriate Region Definition (RD) attributes. Try doubling the existing values and seeing whether the short-on-storage messages disappear. If they do, you could reduce the values slightly. If, after increasing the values, the short-on-storage messages take longer to appear, you might have a problem with an application that is leaking storage.