The system uses DFSMSdfp MSGDISP to update the display screens on tape drives. DFSMSrmm supplies Assembler source code for IGXMSGEX, the MSGDISP installation exit, that you can modify to include your own functions or you can enable to run with another product's supplied exit code.

IGXMSGEX calls EDGMSGEX, the program that supports the MSGDISP interface. EDGMSGEX is a callable program interface to DFSMSrmm that you can use from the MSGDISP exit. You can run this exit in parallel with another copy of the exit. See Setting up parallel processing for more information. This information describes how to use the interface.