In most cases an SA03 abend is a symptom, not a specific problem itself.
It means that a task is trying to end and it cannot free all of the control blocks (ECB's in this case) that it had previously attached.
This usually shows up in the log when CA Dispatch is being shutdown.
A task or subtask may have previously abended, and even though CA Dispatch recovered from the problem and continued processing, an ECB (event control block) was not freed properly. When the shutdown process tries to free the ECB, the shutdown process abends with the SA03 because the fields or address of the ECB are not valid.
When you see an SA03 abend, you need to look in the syslog and also in all of the CA Dispatch logs for any previous abends or unusual messages. The actual SA03 abend dump is usually not of any use because the original problem that caused the ECB to be stranded in the first place may have happened hours before the SA03.
No other followup is needed for the SA03. There may be a response needed if you can identify the original cause.