In systems running under JES2, you can define two kinds of pools: data set pools and volume pools. Data set pools and volume pools are known as user-defined pools. You can define these pools at any time, either during the startup procedure or after DFSMShsm has been started. Similarly, you can use the ADDVOL command to add volumes to DFSMShsm control at any time.
Any volume that has the AUTORECALL subparameter in its ADDVOL command is eligible to be used for recall of any data set that is not restricted to a pool of volumes. This provides a kind of default pool.