NUMBUFG parameter: Difference between revisions
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==Description== | ==Description== | ||
<p> | <p> | ||
Allocate | Allocate this number of buffer pool buffers above the bar (ATB).</p> | ||
<ul> | |||
<li>Prior to version 7.7 of Model 204: | |||
<p> | <p> | ||
<var>NUMBUFG</var> specifies the number of buffer pool buffers built ATB, while the number of buffer pool buffers built BTB is based on the setting of <var>[[MINBUF parameter|MINBUF]]</var>, <var>[[MAXBUF parameter|MAXBUF]]</var>, and <var>[[SPCORE parameter|SPCORE]]</var>.</p></li> | |||
<li>As of version 7.7: | |||
<p> | <p> | ||
For | If <var>NUMBUFG</var> is specified, no buffer pool buffers are built BTB; all buffers are ATB. Model 204 obtains exactly the <var>NUMBUFG</var> number of buffers. </p> | ||
<p> | |||
In this case, <var>NUMBUFG</var> essentially replaces the BTB parameters: <var>NUMBUF</var> and <var>MINBUF</var> are automatically reset to 0, and <var>MAXBUF</var> and <var>SPCORE</var> are ignored. </p> | |||
</li> | |||
</ul> | |||
===Setting NUMBUFG=== | |||
<p> | |||
The maximum number of buffers is <code>2**31/3</code>, or <code>715,827,882</code>, which limits buffer pools to 4.2 terabytes or less.</p> | |||
<p> | |||
The minimum number of ATB buffers is: </p> | |||
<p class="code">[[NLRUQG parameter|NLRUQG]] * (([[NSERVS parameter|NSERVS]] + [[NSUBTKS parameter|NSUBTKS]]) * [[MAXOBUF parameter|MAXOBUF]] + 15) | |||
</p> | |||
<p> | |||
If you set <var>NUMBUFG</var> to a value lower than the minimum, the value is reset to the calculated value and you receive messages like the following: </p> | |||
<p class="code">*** M204.2756: NUMBUFG reset to NLRUQG * ((NSERVS + NSUBTKS) * MAXOBUF + 15) | |||
= 1 * ((2+9) * 4 + 15) = 59 | |||
*** M204.0075: Initialization completed. Buffers = 0+59 | |||
</p> | |||
<blockquote class="note"><b>Note:</b> | |||
<p>If you set <var>NUMBUFG</var> greater than 0: </p> | |||
<ul> | |||
<li>The X'02' bit of the <var>[[XMEMOPT parameter|XMEMOPT]]</var> parameter (the default), must also be set. </li> | |||
<li>The [[File Load utility: FLOD and FILELOAD commands|FLOD and FILELOAD commands]] and [[Fast/Reload]] are not available due to 64-bit addressing conflicts. This particular restriction is removed in V7.7 and later releases. | |||
</ul> | |||
</blockquote> | |||
==See also== | |||
For more information about setting <var>NUMBUFG</var>, see [[Defining the runtime environment (CCAIN)#Using 64-bit addressing and Above the Bar (ATB) storage|Using 64-bit addressing and Above the Bar (ATB) storage]]. | |||
[[Category:System parameters]] | [[Category:System parameters]] | ||
[[Category:Parameters]] | [[Category:Parameters]] | ||
Latest revision as of 14:49, 26 August 2020
Number of above-the-bar buffers
Summary
- Default value
- 0
- Parameter type
- System
- Where set
- Not resettable
- Related products
- All
- Introduced
- Model 204 V7.1
Description
Allocate this number of buffer pool buffers above the bar (ATB).
- Prior to version 7.7 of Model 204:
NUMBUFG specifies the number of buffer pool buffers built ATB, while the number of buffer pool buffers built BTB is based on the setting of MINBUF, MAXBUF, and SPCORE.
- As of version 7.7:
If NUMBUFG is specified, no buffer pool buffers are built BTB; all buffers are ATB. Model 204 obtains exactly the NUMBUFG number of buffers.
In this case, NUMBUFG essentially replaces the BTB parameters: NUMBUF and MINBUF are automatically reset to 0, and MAXBUF and SPCORE are ignored.
Setting NUMBUFG
The maximum number of buffers is 2**31/3, or 715,827,882, which limits buffer pools to 4.2 terabytes or less.
The minimum number of ATB buffers is:
NLRUQG * ((NSERVS + NSUBTKS) * MAXOBUF + 15)
If you set NUMBUFG to a value lower than the minimum, the value is reset to the calculated value and you receive messages like the following:
*** M204.2756: NUMBUFG reset to NLRUQG * ((NSERVS + NSUBTKS) * MAXOBUF + 15) = 1 * ((2+9) * 4 + 15) = 59 *** M204.0075: Initialization completed. Buffers = 0+59
Note:
If you set NUMBUFG greater than 0:
- The X'02' bit of the XMEMOPT parameter (the default), must also be set.
- The FLOD and FILELOAD commands and Fast/Reload are not available due to 64-bit addressing conflicts. This particular restriction is removed in V7.7 and later releases.
See also
For more information about setting NUMBUFG, see Using 64-bit addressing and Above the Bar (ATB) storage.