EQAZ183E You are attempting to deregister the last transaction, which will free up the class you have been assigned. However, your private region is still started. Please STOP your region and try again.

Explanation

An IMS message class is reserved for use if any transaction is registered for debugging using IMS Transaction Isolation facility. The request made would deregister the last transaction and release the message class. However, the private message region is still started. When another user who registers for a transaction receives the released message class and starts a private message region serving the class, unpredictable results can happen.