This step is only required if you have JES3 managed tape devices and do not use deferred tape mounting. With deferred tape mounting, either allocation processing issues or OPEN processing issues the mount requests and the tape drive displays are correct.

JES3 updates the drive display before it issues the IAT5210 mount message, so the drive display might not contain the pool that you select in your exit.

DFSMSrmm provides three methods for updating the IAT5210 message and the tape drive display. Using the DFSMSrmm supplied USERMOD EDGUX71 to IATUX71 is the preferred method for updating the IAT5210 message with the correct exit selected pool. The exit selected pool is used to update the tape drive displays when selection is based on the IAT5210 message. See Running DFSMSrmm with JES3 for information about installing and using DFSMSrmm-supplied JES3 USERMODs.