Obtaining improved data transfer to and from a hiperspace

By specifying the HSPALET parameter on the HSPSERV macro, a program can get faster data movement between central storage and expanded storage. If the data identified on HSPSERV is in expanded storage, HSPSERV uses the move-page facility. If the data is in auxiliary storage, the data transfer still occurs, but without using the move-page facility.

Through the IOSADMF macro, a program can use ADMF to get more efficient data movement between central and expanded storage. Data transfer with the ADMF might be more efficient depending on the number of pages of data you want to transfer.

The IOSADMF macro provides a programming interface to the ADMF. IOSADMF can be used with standard and ESO hiperspaces. With IOSADMF, programs that buffer large amounts of storage in hiperspaces become more efficient because of reduced overall processor use. Processor cycles previously used to move data now become available for the system or other programs to use.

Programs that want to reduce processor time for buffer management, but that find the response time associated with I/O buffering unacceptable, will find the IOSADMF service particularly useful. However, IBM® recommends that you design programs that move data to use either the ADMF (IOSADMF macro) or the move-page facility (HSPSERV macro) for the following reasons:

You cannot use IOSADMF to transfer data unless data already is stored in the hiperspace. Therefore, under certain circumstances, you must use HSPSERV before using IOSADMF to transfer data.
If the ADMF is not available, your program can attempt the data transfer again by issuing HSPSERV.
If your program moves variable amounts of data, you might want to design your program to determine which facility best matches each data transfer request.

Which facility best matches your request depends on the number of pages you want to transfer. When the ADMF is available and the program issues IOSADMF to move data, the system determines which facility is appropriate by comparing the number of pages with a system-specific value. If you want to know what that value is so your program can determine which facility to use, issue IOSADMF with the CROSSOVER parameter, and the system returns the value to you.

z/OS MVS Programming: Authorized Assembler Services Reference EDT-IXG describes the HSPSERV macro and the IOSADMF macro.