NumberOfBuffers (Dataset property): Difference between revisions
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{{Template:Dataset:NumberOfBuffers subtitle}} | |||
This property indicates the number of in-core buffers to be used to hold | This property indicates the number of in-core buffers to be used to hold | ||
input or output blocks for the <var>Dataset</var>. | input or output blocks for the <var>Dataset</var>. | ||
| Line 5: | Line 6: | ||
An attempt to set it while the dataset is not closed results in request | An attempt to set it while the dataset is not closed results in request | ||
cancellation. | cancellation. | ||
== | ==Syntax== | ||
{{Template:Dataset:NumberOfBuffers syntax}} | |||
===Syntax terms=== | ===Syntax terms=== | ||
<table class="syntaxTable"> | <table class="syntaxTable"> | ||
<tr><th>% | <tr><th>%currentNumber</th> | ||
<td>A variable to receive the number of buffers for the <var> | <td>A variable to receive the number of buffers for the <var class="term">dataset</var> object. | ||
</td></tr> | </td></tr> | ||
<tr><th> | <tr><th>dataset</th> | ||
<td>A reference to an instance of a <var>Dataset</var> object. | <td>A reference to an instance of a <var>Dataset</var> object. | ||
</td></tr> | |||
<tr><th>newNumber</th> | |||
<td>A variable to be used to set thenumber of buffers for the <var class="term">dataset</var> object. | |||
</td></tr></table> | </td></tr></table> | ||
==Usage | |||
==Usage notes== | |||
<ul> | <ul> | ||
<li>The default for <var>NumberOfBuffers</var> is 1. | <li>The default for <var>NumberOfBuffers</var> is 1. | ||
| Line 32: | Line 32: | ||
<var>[[BlockSize (Dataset property)|BlockSize]]</var> in bytes times its <var>NumberOfBuffers</var>. | <var>[[BlockSize (Dataset property)|BlockSize]]</var> in bytes times its <var>NumberOfBuffers</var>. | ||
</ul> | </ul> | ||
==See also== | |||
{{Template:Dataset:NumberOfBuffers footer}} | |||
Latest revision as of 22:31, 20 May 2011
Number of buffers to use for i/o (Dataset class)
This property indicates the number of in-core buffers to be used to hold
input or output blocks for the Dataset.
It is only settable while the object is in the Closed state.
An attempt to set it while the dataset is not closed results in request
cancellation.
Syntax
%currentNumber = dataset:NumberOfBuffers dataset:NumberOfBuffers = newNumber
Syntax terms
| %currentNumber | A variable to receive the number of buffers for the dataset object. |
|---|---|
| dataset | A reference to an instance of a Dataset object. |
| newNumber | A variable to be used to set thenumber of buffers for the dataset object. |
Usage notes
- The default for NumberOfBuffers is 1. This causes all block reads from or writes to the dataset to be synchronous on a thread level.
- NumberOfBuffers must be a value between 1 and 255, inclusive.
- If NumberOfBuffers is set to a value greater than 99 on a system that does not support 31-bit BSAM, it is silently set down to 99.
- The buffers for a dataset are allocated in virtual storage. The amount of virtual storage used for the buffers is the dataset's BlockSize in bytes times its NumberOfBuffers.