File Control Table (File architecture): Difference between revisions
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<li>The current file [[BROADCAST command: Sending a file message|broadcast]] message (if any), displayed when the file is [[OPEN FILE command|opened]]. </li> | <li>The current file [[BROADCAST command: Sending a file message|broadcast]] message (if any), displayed when the file is [[OPEN FILE command|opened]]. </li> | ||
</ul> | </ul> | ||
<p>The remaining seven pages of the FCT are empty. They were used in very early versions of M204, but are now 'Reserved for Future Use'.</p> | |||
[[Category:File architecture]] | [[Category:File architecture]] | ||
Revision as of 19:22, 6 March 2015
The File Control Table contains the file parameter settings, data set or file definition names of all data sets in the file, the status of the file, and other control information.
The FCT is 8 pages.
The first page of the FCT is the File Parameter List (FPL) page, which contains:
- The File Parameter List holding the current parameter settings for the file
- The Logical Page Map (LPM) which shows the distribution of the pages within the file
- The data sets list (DSL) comprising the name and number of pages in each data set
- The shared DASD enqueue list, which:
- Controls access to the file by multiple jobs, potentially running on different processors that share the DASD device upon which the file data sets reside
- Contains the enqueue level of each of those jobs. The ENQCTL command enables you to display the enqueue list.
- The current file broadcast message (if any), displayed when the file is opened.
The remaining seven pages of the FCT are empty. They were used in very early versions of M204, but are now 'Reserved for Future Use'.