$UnPost: Difference between revisions
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< | <var>$UnPost</var> resets a specified Event Control Block (ECB) to an unposted state, meaning that the event has not yet occurred or has not recurred. Resets the post code to zero. | ||
==Syntax== | |||
<p class="code">$UnPost(ECB-number) | <p class="code">$UnPost(ECB-number) | ||
</p> | </p> | ||
<p>Where:</p> | <p> | ||
Where:</p> | |||
<p>ECB-number is a numeric value from one to the NECBS parameter that identifies the ECB to be unposted. The ECB-number can be expressed as a numeric literal, a literal enclosed in quotation marks, a %variable, or a field name.</p> | <p>ECB-number is a numeric value from one to the NECBS parameter that identifies the ECB to be unposted. The ECB-number can be expressed as a numeric literal, a literal enclosed in quotation marks, a %variable, or a field name.</p> | ||
<p>Use the <var>$UnPost</var> function to unpost a specified, numbered ECB. An ECB must be unposted before another post or wait on this ECB takes place. The <var>$Post</var> and <var>$Wait</var> functions do not unpost an ECB, so that a subsequent wait on the same ECB cannot take place, because the ECB is still posted from the previous posting. </p> | ==Usage== | ||
<p>Use the <var>$Post</var>, <var>$UnPost</var>, and $ | <p> | ||
Use the <var>$UnPost</var> function to unpost a specified, numbered ECB. An ECB must be unposted before another post or wait on this ECB takes place. The <var>$Post</var> and <var>$Wait</var> functions do not unpost an ECB, so that a subsequent wait on the same ECB cannot take place, because the ECB is still posted from the previous posting. </p> | |||
<p>Use the <var>$Post</var>, <var>$UnPost</var>, and <var>$Wait</var> functions to coordinate processing between threads for numbered ECBs. For the extended quiesce ECB, QZSIG, only the <var>$Wait</var> and <var>$Post</var> functions are valid.</p> | |||
<p> | <p> | ||
<var>$UnPost</var> does not reset the contents of the post code or string data set by the <var>$Post</var> or $ | <var>$UnPost</var> does not reset the contents of the post code or string data set by the <var>$Post</var> or <var>$EcbDset</var> functions for the specified ECB.</p> | ||
<p class="note"><b>Note:</b> Even in a non-multiprocessing environment, the <var>$UnPost</var> function should be used with extreme care. Unposting an ECB while users are waiting on it may keep users in a wait state forever or until the next <var>$Post</var> function is issued.</p> | <p class="note"><b>Note:</b> Even in a non-multiprocessing environment, the <var>$UnPost</var> function should be used with extreme care. Unposting an ECB while users are waiting on it may keep users in a wait state forever or until the next <var>$Post</var> function is issued.</p> | ||
<p> | <p> | ||
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<th>Meaning</th> | <th>Meaning</th> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">0 </td> | <td align="right">0 </td> | ||
<td>Success</td> | <td>Success</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">2 </td> | <td align="right">2 </td> | ||
<td>Bad argument specified</td> | <td>Bad argument specified</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">3</td> | <td align="right">3</td> | ||
<td>NECBS parameter is not specified or is zero</td> | <td>NECBS parameter is not specified or is zero</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">4 </td> | <td align="right">4 </td> | ||
<td>The first argument is less than one or greater than the NECBS parameter</td> | <td>The first argument is less than one or greater than the NECBS parameter</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">5 </td> | <td align="right">5 </td> | ||
<td>NUSERS = 1</td> | <td>NUSERS = 1</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">8 </td> | <td align="right">8 </td> | ||
<td>No argument specified</td> | <td>No argument specified</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td align="right">12</td> | <td align="right">12</td> | ||
Revision as of 19:51, 8 September 2014
$UnPost resets a specified Event Control Block (ECB) to an unposted state, meaning that the event has not yet occurred or has not recurred. Resets the post code to zero.
Syntax
$UnPost(ECB-number)
Where:
ECB-number is a numeric value from one to the NECBS parameter that identifies the ECB to be unposted. The ECB-number can be expressed as a numeric literal, a literal enclosed in quotation marks, a %variable, or a field name.
Usage
Use the $UnPost function to unpost a specified, numbered ECB. An ECB must be unposted before another post or wait on this ECB takes place. The $Post and $Wait functions do not unpost an ECB, so that a subsequent wait on the same ECB cannot take place, because the ECB is still posted from the previous posting.
Use the $Post, $UnPost, and $Wait functions to coordinate processing between threads for numbered ECBs. For the extended quiesce ECB, QZSIG, only the $Wait and $Post functions are valid.
$UnPost does not reset the contents of the post code or string data set by the $Post or $EcbDset functions for the specified ECB.
Note: Even in a non-multiprocessing environment, the $UnPost function should be used with extreme care. Unposting an ECB while users are waiting on it may keep users in a wait state forever or until the next $Post function is issued.
The following return codes apply to the $UnPost function:
| Return code | Meaning |
|---|---|
| 0 | Success |
| 2 | Bad argument specified |
| 3 | NECBS parameter is not specified or is zero |
| 4 | The first argument is less than one or greater than the NECBS parameter |
| 5 | NUSERS = 1 |
| 8 | No argument specified |
| 12 | Invalid argument CPQZ or invalid argument following QZSIG |