Closing VSAM or BDAM files

You can close files with a CLOSE command, with or without the FORCE option.

Closing files normally

You can close a file explicitly with one of the following commands

CEMT SET FILE(filename) CLOSED
EXEC CICS SET FILE(filename) CLOSED

The file is closed immediately if there are no transactions using the file at the time of the request. The file is also disabled as part of the close operation, this form of disablement showing as UNENABLED on a CEMT display. This prevents subsequent requests to access the file implicitly reopening it.

A transaction in the process of executing a VSAM or BDAM request, or executing a series of connected requests, is said to be a user of the file. For example,: a transaction is a user during the execution of the following requests

READ UPDATE ---- REWRITE
STARTBROWSE ---- READNEXT ... ---- ENDBROWSE

A transaction is also a user of a file if it completes a recoverable change to the file but has not yet reached a sync point or the end of the transaction.

If there are users at the time of the close request, the file is not closed immediately. CICS® waits for all current users to complete their use of the file. The file is placed in an UNENABLING state to deny access to new users but allow existing users to complete their use of the file. When the last user has finished with the file, the file is closed and UNENABLED. If a transaction has made recoverable changes to a file and then suffered a failure during syncpoint, the unit of work is shunted, and the file can be closed at this point.

Closing files using the FORCE option

You can also close a file using one of the following commands

CEMT SET FILE(filename) FORCECLOSE
EXEC CICS SET FILE(filename) CLOSED FORCE

Any transactions that are current users of the file are abended and allowed to back out any changes as necessary, and the file is then closed and UNENABLED. A file UNENABLED as a result of a CLOSE request can be reenabled subsequently if an explicit OPEN request is made.

Note:
Closing a file using the FORCE option causes tasks of any current users of the file to be terminated immediately by the CICS task FORCEPURGE mechanism. Data integrity is not guaranteed with this mechanism. In some extreme cases (for example, if an error occurs during backout processing), CICS might terminate abnormally. For this reason, closing files using the FORCE option should be restricted to exceptional circumstances.

[[ Contents Previous Page | Next Page Index ]]