SERVGSZ parameter: Difference between revisions
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(Changed description of SERVGSZ from server non-swappable size to server swappable size. Added a line for SERVNSA since SERVNSSZ was there also.) |
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{{Template:SERVGSZ parameter subtitle}} | {{Template:SERVGSZ parameter subtitle}} | ||
==Summary== | ==Summary== | ||
<dl> | <dl> | ||
<dt>Default value | <dt>Default value | ||
<dd> | <dd>0 | ||
<dt>Parameter type | <dt>Parameter type | ||
<dd>System | <dd>System | ||
<dt>Where set | <dt>Where set | ||
<dd>User 0 parameter line | <dd>On User 0's parameter line | ||
<dt>Related products | <dt>Related products | ||
<dd>All | <dd>All | ||
<dt>Introduced | <dt>Introduced | ||
<dd><var class="product">Model 204</var> | <dd><var class="product">Model 204 V7.5</var> | ||
</dl> | </dl> | ||
==Description== | |||
<p>The <var>SERVGSZ</var> parameter, along with the <var>SERVGA</var> parameter, controls swappable above-the-bar (in memory with address greater than 2G) server areas.</p> | |||
<ul> | |||
<li> | |||
<var>SERVGSZ</var> (server swappable size) is the amount of space in bytes required for the swappable above-the-bar server tables per server. The total amount of storage allocated for swappable above-the-bar server areas equals <var>SERVGSZ</var> rounded to 4K and multiplied by [[NSERVS parameter|NSERVS]]. | |||
When sizing <var>SERVGSZ</var> you should use the largest sum of swappable above-the-bar server table sizes that might be needed.</li> | |||
<li><var>[[SERVGA parameter|SERVGA]]</var> (server swappable areas) indicates the server tables that you want to be above the bar.</li> | |||
</ul> | |||
For reference purposes: | |||
<ul> | |||
<li>The [[SERVNSSZ parameter]] controls the size of the <b>non-swappable</b> above-the-bar server areas. | |||
<li>The [[SERVNSA parameter]] controls which tables are in the <b>non-swappable</b>, above-the-bar server areas. | |||
</ul> | |||
{{Template:SERVGA/SERVGSZ common}} | |||
[[Category:System parameters]] | |||
[[Category:Parameters]] | [[Category:Parameters]] | ||
Latest revision as of 19:14, 4 November 2014
ATB server size maximum
Summary
- Default value
- 0
- Parameter type
- System
- Where set
- On User 0's parameter line
- Related products
- All
- Introduced
- Model 204 V7.5
Description
The SERVGSZ parameter, along with the SERVGA parameter, controls swappable above-the-bar (in memory with address greater than 2G) server areas.
- SERVGSZ (server swappable size) is the amount of space in bytes required for the swappable above-the-bar server tables per server. The total amount of storage allocated for swappable above-the-bar server areas equals SERVGSZ rounded to 4K and multiplied by NSERVS. When sizing SERVGSZ you should use the largest sum of swappable above-the-bar server table sizes that might be needed.
- SERVGA (server swappable areas) indicates the server tables that you want to be above the bar.
For reference purposes:
- The SERVNSSZ parameter controls the size of the non-swappable above-the-bar server areas.
- The SERVNSA parameter controls which tables are in the non-swappable, above-the-bar server areas.
While it might seem odd to have above-the-bar swappable server areas, especially if swapping to above-the-bar memory, placing NTBL and QTBL in a swappable area can save quite a bit of real memory. This is especially true if the RESPAGE parameter is set to a non-zero value and there are significantly more users (NUSERS) than servers (NSERVS). In such a case, most swapped out users would either be using a resident (shared) NTBL and QTBL, or they would be logged out and only using a single 4K page. As such, reserving the amount of space required for NTBL and QTBL (which can typically get quite large) in the non-swappable above-the-bar area for all the swapped out users can waste a significant amount of real storage.