z/OS MVS Programming: Extended Addressability Guide
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Read and write operations for standard hiperspaces

z/OS MVS Programming: Extended Addressability Guide
SA23-1394-00

After the write operation for standard hiperspaces, the system does not preserve the data in the address space. It assumes that you have another use for that buffer area, such as using it as the target of another HSPSERV SREAD operation.

After the read operation for standard hiperspaces, the system gives you a choice of saving the source data in the hiperspace. If you will use the data in the hiperspace again, ask the system to preserve the data; specify RELEASE=NO on HSPSERV SREAD. Unless a subsequent SWRITE request changes the data in the source area, that same data will be available for subsequent SREAD requests. RELEASE=NO provides your program with a backup copy of the data in the hiperspace.

If you specify RELEASE=YES on HSPSERV SREAD, the system releases the hiperspace pages after the read operation and returns the expanded storage (or auxiliary storage) that backs the source area in the hiperspace. RELEASE=YES tells the system that your program does not plan to use the source area in the hiperspace as a copy of the data after the read operation. Note that when a hiperspace is not fetch-protected, HSPSERV SREAD,RELEASE=NO works even when the program's PSW key does not match the storage key of the hiperspace.

To use the HSPSERV macro without an ALET for a non-shared standard hiperspace, the buffer area in the address space must be in the program's home address space. That is, the program cannot be in cross memory mode (where PASN is not equal to HASN).

A program cannot issue a HSPSERV SWRITE to an area of a hiperspace that has a DIV SAVE in progress.

See Example of creating a standard hiperspace and using It for an example of the HSPSERV SREAD and HSPSERV SWRITE macros.

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