When renaming a data set, build a volume list in virtual storage. The volume list consists of an entry for each volume on which the data set resides. If you are renaming an SMS-managed data set, specify at least one SMS-managed volume in the list. The first two bytes of the list indicate the number of entries in the list. Each 12-byte entry consists of a 4-byte device code (the UCBTYP field from the volume's UCB), a 6-byte volume serial number, and a 2-byte rename status code that should be initialized to zero.

Volumes are processed according to their order in the volume list. If a volume is not mounted, a message is issued to the operator requesting that the volume be mounted. This only occurs when you indicate the direct access device on which unmounted volumes are to be mounted by loading register 0 with the address of the UCB of the device. (The device must be allocated to your job.) If you do not load register 0 with a UCB address, its contents must be zero, and at least one of the volumes in the volume list must be mounted before the RENAME macro instruction is issued. Use the address of a UCB, not a UCB copy, in register 0 with this macro. 31-bit programs must pass a clean UCB addr on RENAME, when applicable.

If the requested volume cannot be mounted, the operator replies by indicating that the request cannot be fulfilled. A status code is then set in the last byte of the volume list entry (the second byte of the rename status code) for the unavailable volume, and the next volume indicated in the volume list is processed.