XMEMOPT parameter: Difference between revisions
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<dl> | <dl> | ||
<dt>Default value | <dt>Default value | ||
<dd> | <dd>X'02' if [[Cross-memory_facilities_CRAM_and_M204XSVC#M204XSVC|M204XSVC]] is linked into the nucleus (as of V7.5, M204XSVC is linked into the nucleus by default) | ||
<DD>X'00' if M204XSVC is not linked into the nucleus | |||
<dt>Parameter type | <dt>Parameter type | ||
<dd>System | <dd>System | ||
| Line 11: | Line 12: | ||
<dd>All | <dd>All | ||
<dt>Introduced | <dt>Introduced | ||
<dd><var class="product">Model 204 | <dd><var class="product">Model 204 V2.1</var> or earlier | ||
</dl> | </dl> | ||
==Description== | ==Description== | ||
<p> | <p> | ||
<p>This parameter applies only to z/OS.</p> | This parameter sets the <var class="product">Model 204</var> cross-memory services options that can be invoked during execution of <var class="product">Model 204</var>. </p> | ||
<p> | <p> | ||
<p>Valid settings of XMEMOPT are: | This parameter applies only to z/OS.</p> | ||
<p> | |||
Prior to <var class="product">Model 204</var> 7.5, nonzero settings of <var>XMEMOPT</var> enabled features whose execution was accomplished with a system supervisor call (SVC), and the SVC number was specified as the <var>[[XMEMSVC parameter|XMEMSVC]]</var> parameter value in the Model 204 CCAIN. | |||
Under the default installation of Model 204 as of version 7.5, the <code>M204XSVC</code> module is not installed as an SVC, and specifying an <var>XMEMSVC</var> value is not necessarily required for the <var>XMEMOPT</var> features. </p> | |||
<p> | |||
Valid settings of <var>XMEMOPT</var> are: </p> | |||
<table> | <table> | ||
<tr><th>Setting</th><th>Meaning</th></tr> | <tr class="head"><th>Setting</th><th>Meaning</th></tr> | ||
<tr><th align="right"><var>X'80'</var></th><td>Activates CRAM-XDM.</td></tr> | |||
<tr><th align="right"><var>X'20'</var></th><td>Use SUSPEND / RESUME instead of WAIT / POST for communication between <var class="product">Model 204</var> real subtasks. This option may reduce operating system overhead slightly.</td></tr> | <tr><th align="right"><var>X'80'</var></th> | ||
<tr><th | <td>Activates [[Defining the user environment (CCAIN)#Using CRAM on a z/OS operating system|CRAM-XDM]]. | ||
<tr><th | <p>If the Online and CRAM-XDM load modules are not APF authorized, the X'80' bit is turned off. </p></td></tr> | ||
<tr><th | |||
<tr><th | <tr><th align="right"><var>X'20'</var></th> | ||
<tr><th | <td>Use SUSPEND/RESUME instead of WAIT/POST for communication between <var class="product">Model 204</var> real subtasks. This option may reduce operating system overhead slightly. | ||
<p> | |||
If the Online load module is not APF authorized, the X'20' bit is turned off. </p></td></tr> | |||
<tr><th><var>X'04'</var></th> | |||
<td>Forces initialization of cross-memory environment (M204XSVC). | |||
<p>This bit might be useful for the [[Model 204 environment for UL/DB2#Taking advantage of operating system Cross-Memory Services|UL/DB2 feature]].</p></td></tr> | |||
<tr><th><var>X'03'</var></th> | |||
<td>Invokes both [[Timer PC]] and [[IOS Branch Entry]].</td></tr> | |||
<tr><th><var>X'02'</var></th> | |||
<td>Invokes IOS Branch Entry (recommended for z/OS) to handle all database and [[Using_the_system_scratch_file_(CCATEMP)|CCATEMP]] I/O. | |||
<ul> | |||
<li>If the Online load module is not APF authorized, the X'02' bit is turned off. </li> | |||
<li>As of Model 204 version 7.6, the X'02' setting is required for [[Performance monitoring and tuning#Offloading Model 204 work to zIIP processors|zIIP processing]] and for [[Defining the runtime environment (CCAIN)#Disk buffers and Model 204 storage|allocating Model 204 buffer pool buffers above the bar]]. </li> | |||
</ul></td></tr> | |||
<tr><th><var>X'01'</var></th> | |||
<td>Invokes Timer PC. | |||
<p class="note"><b>Note:</b> As described in the [[Performance monitoring and tuning#Timer PC|Timer PC]] section, this bit is automatically turned off as of version 7.4 of Model 204 if your system supports the ECTG instruction. </p></td></tr> | |||
<tr><th><var>X'00'</var></th> | |||
<td>Disables Model 204 cross-memory services.</td></tr> | |||
</table> | </table> | ||
<p class="note"><b>Note:</b> VIO is incompatible with | <p class="note"><b>Note:</b> VIO is incompatible with IOS Branch Entry and [[Performance monitoring and tuning#EXCPVR|EXCPVR]].</p> | ||
[[Category:System parameters]] | [[Category:System parameters]] | ||
[[Category:Parameters]] | [[Category:Parameters]] | ||
Latest revision as of 22:15, 13 December 2017
Cross-memory PC options
Summary
- Default value
- X'02' if M204XSVC is linked into the nucleus (as of V7.5, M204XSVC is linked into the nucleus by default)
- X'00' if M204XSVC is not linked into the nucleus
- Parameter type
- System
- Where set
- On User 0's parameter line
- Related products
- All
- Introduced
- Model 204 V2.1 or earlier
Description
This parameter sets the Model 204 cross-memory services options that can be invoked during execution of Model 204.
This parameter applies only to z/OS.
Prior to Model 204 7.5, nonzero settings of XMEMOPT enabled features whose execution was accomplished with a system supervisor call (SVC), and the SVC number was specified as the XMEMSVC parameter value in the Model 204 CCAIN.
Under the default installation of Model 204 as of version 7.5, the M204XSVC module is not installed as an SVC, and specifying an XMEMSVC value is not necessarily required for the XMEMOPT features.
Valid settings of XMEMOPT are:
| Setting | Meaning |
|---|---|
| X'80' | Activates CRAM-XDM.
If the Online and CRAM-XDM load modules are not APF authorized, the X'80' bit is turned off. |
| X'20' | Use SUSPEND/RESUME instead of WAIT/POST for communication between Model 204 real subtasks. This option may reduce operating system overhead slightly.
If the Online load module is not APF authorized, the X'20' bit is turned off. |
| X'04' | Forces initialization of cross-memory environment (M204XSVC).
This bit might be useful for the UL/DB2 feature. |
| X'03' | Invokes both Timer PC and IOS Branch Entry. |
| X'02' | Invokes IOS Branch Entry (recommended for z/OS) to handle all database and CCATEMP I/O.
|
| X'01' | Invokes Timer PC.
Note: As described in the Timer PC section, this bit is automatically turned off as of version 7.4 of Model 204 if your system supports the ECTG instruction. |
| X'00' | Disables Model 204 cross-memory services. |
Note: VIO is incompatible with IOS Branch Entry and EXCPVR.