Unit settings
Unit type
Use to specify a device by its generic name, which is an IBM-supplied name that identifies a device by its machine type
and model; for example, 3390. You can select to use the system default device type or enter your preferred device type.
Unit count
Use to specify the number of devices for new data sets. The system uses the unit-count to determine how many devices
to allocate.
Specify a value of P to use the same number of devices specified in the volume list or the volume count
value, whichever is higher. Specifying a value of P causes all volumes for the data set to be mounted in parallel.