The device that a data set resides on is determined as follows:
- For SMS-managed data sets, by the storage
class for the new data set, specified on the STORCLAS parameter of
the DD statement or selected by the installation-written automatic
class selection (ACS) routine for the new data set.
- For non-SMS-managed data sets, by the UNIT
parameter, specified on the DD statement for the new data set, or,
with SMS, by the SMS default unit, when the UNIT parameter is not
specified.