Are you using IMS? Because IMS ROLB abends with user code 3303. This is a controlled abend issued by the program. All changes since the last commit point (IMS CHKP command) are discarded as weill as output messages. If you are in a IMS DC environment all messages retrieved since the last commit point are returned to the message queue. You can verify this by issuing a /DISP at a MTO terminal.
Hope this helps!