A journal is a set of special-purpose sequential files. Journals can contain any and all data that the application program needs to enable subsequent reconstruction of events or data changes. For example, a journal can act as an audit trail, a change-file of database updates and additions, or a record of transactions that are passing through the system (often called a log). Each journal can be written from any task.
Of particular interest are the attributes DiskA and DiskB. These attributes specify the name of the file (in regionName/data) that holds the journal. Both files must be writable, although only one file is used at a time. The file that is in use is set to current (see the DiskAStatus and DiskBStatus attributes). You can request to switch between DiskA and the alternative file in DiskB by using the EXEC CICS® SET JOURNAL or CEMT SET JOURNALNUM commands.
CICS does not empty user journals, so you must clear them when they are no longer required. If CICS is offline, delete the two operating system files that are defined as DiskA and DiskB.