A host can run only one RECYCLE command at a time. One RECYCLE command, however, can run up to 15 recycling tasks simultaneously. Two tape drives are required for each task, one for input and one for output. (Duplex processing requires three tapes drives for each task, one for input and two for output.) The more tape drives you use, the faster recycle processing proceeds.

For example, if you issue a recycle command against a specific tape volume, processing is equivalent to one recycle task, requiring two (or three with duplex processing) tape drives. If you issue a recycle command against all ML2 tape volumes and SETSYS MAXRECYCLETASKS is set to 15, DFSMShsm processes 15 tapes at the same time, requiring 30 (or 45 with duplex processing) tape drives.

The SETSYS MAXRECYCLETASKS parameter allows you to dynamically change the number of recycle tape processing tasks, even during recycle processing, to any number from one to 15. If you decrease the tasking level below what is currently running, tasks are quiesced until the new level is reached. Currently running tasks are not stopped in the middle of the volume set they are processing. The default is two recycle-processing tasks.