There are three mount attributes: permanently resident, reserved,
and removable. The permanently resident or reserved attributes may
be specified in a volume attribute list. The removable attribute automatically
applies to any volume that VATLSTxx does not designate or default
as permanently resident or reserved.
A permanently resident volume is either one that cannot
be physically demounted (that is, a drum, 3344, or 3350) or one that
cannot be demounted until its device is varied offline. Only direct
access volumes can be made permanently resident.
The following volumes are
always marked permanently resident
by NIP. You should therefore specify only the use attribute of these
volumes in a volume attribute list:
- Volumes that cannot be physically demounted (such as a 3350 volume).
- The system residence volume This volume includes the SYS1.SVCLIB
and SYS1.NUCLEUS data sets.
- Volumes that contain these system data sets: SYS1.LINKLIB and
data sets concatenated to it, SYS1.DUMPnn, VIO journaling data set,
page data sets, and swap data sets.
A reserved volume remains mounted until the operator issues
an UNLOAD or a VARY OFFLINE command. A volume is marked reserved
when it is so designated in a volume attribute list, or when the operator
issues a MOUNT command for the volume.
A removable volume can be demounted after its last use in
a job, or when the device on which it is mounted is needed for another
volume. Any volume not designated as either permanently resident
or reserved is considered removable. The operator can change a removable
volume to a reserved volume by issuing the MOUNT command for the volume.
The
use attribute controls the type of request for which
a volume can be assigned:
- a specific volume request.
- a temporary, non-private non-specific volume request.
- a non-temporary, non-private, non-specific volume request.
Three
use attributes are used for allocating these types
of volume requests, as follows:
- A private volume is allocated only to a specific volume
request. For more information about this attribute, see z/OS MVS JCL Reference.
- A public volume is allocated to a temporary, non-specific
volume request (or possibly to a specific volume request). Thus, a
scratch data set would be placed on a public volume.
- A storage volume is allocated primarily to a non-temporary,
non-specific volume request. (A storage volume can also be allocated
to a specific volume request or a temporary non-specific volume request.)
Note: A storage volume is required by the SAVE subcommand of EDIT
for a newly created data set. If a storage volume is not available,
the SAVE subcommand cannot save the data set.