ATTENDED ON or OFF controls whether or not human intervention is expected when new tapes or disk files are needed.
The default is ON.
For unattended backups to disk, BACKUP does not prompt you to add more disk space. If you run out of space, an error occurs and BACKUP halts.
For unattended backups to tape, BACKUP does not prompt for a new tape to be loaded. The SIZE and STACKER options determine what happens if you run out of space.