specifies that space from one of the VSAM data spaces on the volume is to
be assigned to the alternate index's component.
specifies whether the alternate index's components are allocated an amount of
space from the volume's available space (UNIQUE) or from a VSAM data
space's available space (SUBALLOCATION).
specifies that a VSAM data space is to be built and assigned exclusively to
each component of the alternate index. The data space is created when
the alternate index is defined. The alternate index's volume(s) must be
VSAM builds a DSCB in the volume's table of contents (VTOC) to describe
the data space. The name of the data space, which is the same as the
component's name, is put in the DSCB. A subentry is added to the volume
entry (in the VSAM catalog) to describe the VSAM data space.