APSYPAGE parameter: Difference between revisions
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==Description== | ==Description== | ||
<p>Activates the APSY Precompiled Procedures in Storage feature by specifying a number of 4K operating system pages.</p> | <p> | ||
<p>For IBM z/OS systems only.</p> | Activates the APSY Precompiled Procedures in Storage feature by specifying a number of 4K operating system pages.</p> | ||
<p>APSYPAGE was implemented to take advantage of the MVPG machine language instruction which moved an entire hardware page (4K) with a single instruction and which, at the time, had significantly better performance than the stream-oriented moves used by standard APSY load. However, recent hardware models actually seem to have better performance for the stream-oriented moves so it is recommended that customers disable the APSYPAGE feature by setting APSYPAGE to 0.</p> | <p> | ||
For IBM z/OS systems only.</p> | |||
<p> | |||
<var>APSYPAGE</var> was implemented to take advantage of the <code>MVPG</code> machine language instruction which moved an entire hardware page (4K) with a single instruction and which, at the time, had significantly better performance than the stream-oriented moves used by standard APSY load. However, recent hardware models actually seem to have better performance for the stream-oriented moves so it is recommended that customers disable the <var>APSYPAGE</var> feature by setting <var>APSYPAGE</var> to 0.</p> | |||
<p>When switching between using and not using <var>APSYPAGE</var>, the number of in-memory CCATEMP pages (<var>[[TEMPPAGE parameter|TEMPPAGE]]</var>) should be adjusted to compensate for the pages used or not used by <var>APSYPAGE</var>. That is, if <var>APSYPAGE</var> is set to zero, <var>TEMPPAGE</var> should be increased by the corresponding amount, and if <var>APSYPAGE</var> is set to a non-zero value, <var>TEMPPAGE</var> can be decreased by the corresponding amount. </p> | |||
<p class="note"><b>Note:</b> The units for <var>TEMPPAGE</var> are 6184 (<var>[[PAGESZ parameter|PAGESZ]]</var>) bytes while the units for <var>TEMPPAGE</var> are 4096 (hardware page size) bytes, so <var>TEMPPAGE</var> units should be multiplied by 1.5 to convert them to <var>APSYPAGE</var> units, and <var>APSYPAGE</var> units should be divided by 1.5 to convert them to <var>TEMPPAGE</var> units. 4096 times 1.5 equals 6144, but that is actually the amount used on each <var>TEMPPAGE</var> page — 40 bytes are used as page trailers and not used to hold actual data.</p> | |||
[[Category:System parameters]] | [[Category:System parameters]] | ||
[[Category:Parameters]] | [[Category:Parameters]] | ||
Revision as of 16:40, 18 December 2015
APSYPAGE is obsolete as of 7.6
Summary
- Default value
- 0
- Parameter type
- System
- Where set
- On User 0's parameter line
- Related products
- All
- Introduced
- Model 204 V5.1
Description
Activates the APSY Precompiled Procedures in Storage feature by specifying a number of 4K operating system pages.
For IBM z/OS systems only.
APSYPAGE was implemented to take advantage of the MVPG machine language instruction which moved an entire hardware page (4K) with a single instruction and which, at the time, had significantly better performance than the stream-oriented moves used by standard APSY load. However, recent hardware models actually seem to have better performance for the stream-oriented moves so it is recommended that customers disable the APSYPAGE feature by setting APSYPAGE to 0.
When switching between using and not using APSYPAGE, the number of in-memory CCATEMP pages (TEMPPAGE) should be adjusted to compensate for the pages used or not used by APSYPAGE. That is, if APSYPAGE is set to zero, TEMPPAGE should be increased by the corresponding amount, and if APSYPAGE is set to a non-zero value, TEMPPAGE can be decreased by the corresponding amount.
Note: The units for TEMPPAGE are 6184 (PAGESZ) bytes while the units for TEMPPAGE are 4096 (hardware page size) bytes, so TEMPPAGE units should be multiplied by 1.5 to convert them to APSYPAGE units, and APSYPAGE units should be divided by 1.5 to convert them to TEMPPAGE units. 4096 times 1.5 equals 6144, but that is actually the amount used on each TEMPPAGE page — 40 bytes are used as page trailers and not used to hold actual data.