PAGEADD command

PAGEADD adds auxiliary storage space (local page data sets) to the system. The page data sets added remain available to the system until you IPL with the CLPA (create link pack area) option, IPL with the CVIO (clear virtual I/O) option, or issue a PAGEDEL command. PAGEADD can also direct VIO pages away from a page data set that is being added.

Use the PAGEADD command only at the request of your system programmer.

You might need to add auxiliary storage space if any of these conditions exist:

The planned system load increases.
The space provided during system initialization proves insufficient.
Space is lost because of a hardware failure.

If the system detects a shortage of available auxiliary storage space, it issues the following message:

IRA200I AUXILIARY STORAGE SHORTAGE

The system rejects LOGONs and START commands until the shortage is relieved. If the shortage increases, the system issues the following message:

IRA201I CRITICAL AUXILIARY STORAGE SHORTAGE

The system rejects LOGONs and START commands and might delay the starting of certain initiators until the shortage is relieved.

Requested data sets are placed in use in the order specified in the command. The system informs you when each is available for use.

The number of page data sets that can be in use by the system is limited by the number specified on the PAGTOTL system parameter. (See z/OS MVS Initialization and Tuning Guide.) If these limits are exceeded, the system issues a message, and you cannot add any more data sets of that type during this IPL. However, if the limit has been exceeded for one type of data set, you could still add data sets of the other type.

If your paging device contains a subsystem cache, it is important to note that the PAGEADD command determines the status of the subsystem cache and resets it, if necessary. However, MVS™ does not set the subsystem cache on if it was powered off with the IDCAMS command SETCACHE SUBSYSTEM OFF. MVS resets the data in the cache only under certain circumstances, such as at a cold start or at the first issuance of a PAGEADD command to the device.

The page data sets must be defined before you can issue the PAGEADD command. If the volume containing the data set is not mounted before you enter the command, the system issues a mount message.

A data set that is draining, as the result of a PAGEDEL DRAIN command, can be made read/write again by issuing a PAGEADD for the data set. A data set that has been marked BAD cannot be made read/write again with the PAGEADD command.

When you issue a PAGEADD command for a data set previously deleted with a PAGEDEL command, the system might indicate that some slots are already in use on the newly allocated data set. These slots contain pages that the system has migrated to another data set but that the owner has not yet referenced. Once the owner references the page, the system frees the slot both from the newly allocated data set and from the data set on which the page actually resides.

Use the DISPLAY ASM command to identify the page data sets the system is currently using.