EQAZ167E The chosen transaction is not assigned to a class which has an active message region. Therefore, z/OS® Debugger cannot use an active region to build the debugging region.

Explanation

The IMS Transaction Isolation facility uses the current execution environment for the selected transaction to clone a new, private message region. z/OS Debugger cannot find an active message region that serves the assigned class of the selected transaction. Therefore, z/OS Debugger cannot start your private message region.