Storm-drain effect

In some situations, your Db2 applications must be sensitive to a resource-unavailable condition.

For example, assume that a database is stopped for planned maintenance, and that the application receives SQLCODE -904 from the system and ends normally. If your application ignores the SQLCODE -904 message, CICSPlex® SM might continue to route work to the stopped system because it appears to complete its work rapidly. This is sometimes called the storm-drain effect.

When both of the following conditions are true, the storm drain effect can occur:

The CICS® attachment facility is down.
You are using INQUIRE EXITPROGRAM to avoid AEY9 abends.

Again, because there has not been an abend, it appears as if work completes rapidly at that subsystem.