ALTERNATE3590UNITNAME: Specifying 3590 alternate unit name for a tape copy

Explanation: ALTERNATE3590UNITNAME(unittype1,unittype2) is used to specify the unit name associated with only the IBM® 3590 tape subsystem. When ALTERNATE3590UNITNAME is specified, the alternate tape will be allocated using the specified unit name. This will be done as long as there is no incompatibility in the unit name.

Defaults: None.