The control file created during aggregate backup has exceeded the limit of 15 volumes.
Aggregate backup fails. DFSMShsm processing continues.
The most likely reason that the control file exceeded 15 volumes is because the selection data sets for this aggregate group defined an extremely large quantity of data to be backed up. The definition of this aggregate group should be changed so it does not attempt to back up such a large amount of data. Split this aggregate into 2 or more aggregate groups and reissue the ABACKUP command for each of the new aggregate groups.
DFSMShsm