Mount attributes

Permanently resident — meaning thevolume cannot be demounted. Only direct access volumes can be permanently resident. The following volumes are always permanently resident:
- All volumes that cannot be physically demounted, such as drum storage and fixed disk volumes
- The IPL volume
- The volume containing the system data sets
In the VATLSTxx member, you can assign a permanently-residentvolume any of the three use attributes. If you do not assign a use attribute to a permanently-resident volume, the default is public.
Reserved — meaning the volume is to remain mounted until the operator issues an UNLOAD command.
Both direct access and tape volumes can be reserved because of the MOUNT command; only DASD volumes can be reserved through the VATLSTxx member.

The reserved attribute is usually assigned to a volume that will be used by many jobs to avoid repeated mounting and demounting.

You can assign a reserved direct access volume any of the three use attributes, through the USE parameter of the MOUNT command or the VATLSTxx member, whichever is used to reserve the volume.

A reserved tape volume can only be assigned the use attributes of private or public.
Removable — meaning that the volume is not permanently resident or reserved. A removable volume can be demounted either after the end of the job in which it is last used, or when the unit it is mounted on is needed for another volume.
You can assign the use attributes of private or public to a removable direct access volume, depending on whether VOLUME=PRIVATE is coded on the DD statement: if this subparameter is coded, the use attribute is private; if not, it is public.
You can assign the use attributes of private or public to a removable tape volume under one of the following conditions:
- Private
  - The PRIVATE subparameter is coded on the DD statement.
  - The request is for a specific volume.
  - The data set is nontemporary (not a system-generated data set name, and a disposition other than DELETE).
  Note: The request must be for a tape only data set. If, for example, an esoteric group name includes both tape and direct access devices, a volume allocated to it will be assigned a use attribute of public.
- Public
  - The PRIVATE subparameter is not coded on the DD statement.
  - A nonspecific volume request is being made.
  - The data set is temporary (a system-generated data set name, or a disposition of DELETE).

Table 1 summarizes the mount and use attributes and how they are related to allocation requests.

Table 1. Summary of mount and use attribute combinations
Volume State	Temporary Data Set	Nontemporary data set	How Assigned	How Unmounted
Volume State	Type of Volume Request		How Assigned	How Unmounted
Public and Permanently Resident (see note)	Nonspecific or Specific	Specific	VATLSTxx entry or by default	Always mounted
Private and Permanently Resident (see note)	Specific	Specific	VATLSTxx entry	Always mounted
Storage and Permanently Resident (see note)	Nonspecific or Specific	Nonspecific or Specific	VATLSTxx entry	Always mounted
Public and Reserved (Tape and direct access)	Nonspecific or Specific	Specific	Direct access: VATLSTxx entry or MOUNT command; Tape: MOUNT command	UNLOAD or VARY OFFLINE commands
Private and Reserved (Tape and direct access)	Specific	Specific	Direct access: VATLSTxx entry or MOUNT command ;Tape: MOUNT command	UNLOAD or VARY OFFLINE commands
Storage and Reserved (see note)	Nonspecific or Specific	Nonspecific or Specific	VATLSTxx entry or MOUNT command	UNLOAD or VARY OFFLINE commands
Public and Removable (Tape and direct access)	Nonspecific or Specific	Specific	VOLUME=PRIVATE is not coded on the DD statement. (For tape, nonspecific volume request and a temporary data set also cause this assignment.)	When unit is required by another volume; or by UNLOAD or VARY OFFLINE commands.
Private and Removable (Tape and direct access)	Specific	Specific	VOLUME=PRIVATE is coded on the DD statement. (For tape, a specific volume request or a nontemporary data set also cause this assignment).	At job termination for direct access; at step termination or dynamic unallocation for tape (unless VOL=RETAIN or a disposition of PASS was specified); or when the unit is required by another volume.