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Support for 64-bit virtual storage addresses

z/Series architecture supports the use of 64-bit registers and switching between 31-bit and 64-bit addressing modes. z/OS 1.2 introduced support for requesting 64-bit virtual storage, as well as controls on the use of storage "above the bar" via the MEMLIMIT JCL parameter and new facilities in the IEFUSI user exit. SDSF on z/OS reports the MEMLIMIT setting for active jobs and this information is also retained in SMF type 30 records.

The IARV64 macro, introduced with z/OS 1.2, supports managing 64-bit memory objects from programs running in 31 or 64-bit addressing mode.


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