$UnPost

$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

See also

The ECB-related $functions are:

• $EcbDGet
• $EcbDSet
• $EcbTest
• $Post
• $UnPost
• $Wait