This area contains tables and queues relating to the entire system. Its contents are highly dependent on configuration and job requirements at an installation. The total amount of virtual storage and number of private virtual storage address spaces are two of the factors that affect the system's use of SQA.

The SQA is allocated directly below the nucleus; the extended SQA is allocated directly above the extended nucleus.

If the specified amount of virtual storage is not available during initialization, a warning message will be issued. The SQA parameter may be respecified at that time from the operator's console.

Virtual SQA is allocated as a number of 64K blocks to be added to the minimum system requirements for SQA. If the SQA required by the system configuration exceeds the amount that has been reserved through the SQA parameter, the system attempts to allocate additional virtual SQA from the CSA area. When certain storage thresholds are reached, as explained in SQA/CSA thresholds, the system stops creating new address spaces. When SQA is in use, it is fixed in central storage.

The size of the SQA cannot be increased or decreased by the operator during a restart that reuses the previously initialized PLPA (a quick start). The size will be the same as during the preceding IPL.