DSPOPT parameter

Data space options

Summary

Default value

X'01'

Parameter type

System

Where set

On User 0's parameter line

Related products

All

Introduced

Model 204 V5.1

Description

The bits have the following meanings:

Settings	Meaning
X'01'	Use the Assembly Language Move Page (MVPG) facility to move a 4-K page when swapping users to and from CCASERVR. This option applies when using the CCASERVR in Storage feature. With this option enabled, CCASERVR is allocated as one contiguous block of storage, above the bar in 64-bit systems. The size of CCASERVR is calculated by NUSERS*(largest SERVSIZE), and it is logically divided into a collection of 4K pages. When users are server swapped to or from CCASERVR, their server slot in CCASERVR might occupy multiple, non-contiguous blocks of 4K pages. This algorithm tends to “front load” CCASERVR, keeping frequently referenced pages at the beginning, and it results in reduced operating-system paging. This management strategy reduces the number of 4K-page moves, keeps the virtual storage allocated to CCASERVR less fragmented, and often requires fewer operating-system-page tables. As of Model 204 version 7.5, this setting is the default. (Previously, X'00' was the default.)
X'02'	Put servers in a hiperspace instead of a dataspace. This setting is applicable only for real dataspaces for non-64-bit systems.
X'04'	Use compression when swapping servers. (New in Model 204 version 7.6) This setting is applicable only for 64-bit in-storage server swapping. When enabled, each table in the server is individually moved based on its usage. In addition, if page fixing is specified for the server swapping memory (the PAGEFIX=X’00000004’ option), only the highwater mark of pages will be fixed.
X'20'	Put APSY precompiled procedures in hiperspace instead of a dataspace. Hiperspace pages can be in real or expanded storage. This option is not valid on IBM z/VSE, and it requires that Model 204 be APF-authorized.
X'40'	Put APSY precompiled procedures in cache hiperspace instead of a scrolling hiperspace. Cache hiperspace pages can reside only in expanded storage, so they are sometimes called ESO (for Expanded Storage Only) hiperspaces. Also, cache hiperspace pages never result in operating system paging. Pages stolen by the operating system are simply discarded, and Model 204 is responsible for replacing the pages from the copy of the precompiled procedures in CCATEMP. This option is not valid on IBM z/VSE, and it requires that Model 204 be APF-authorized.
X'80'	Keep all APSY saved pages in CCATEMP. Set DSPOPT to X'80' only when TEMPPAGE is 0, and then only in unusual circumstances.