CICS data tables

A data table is defined by means of the CEDA DEFINE FILE command. When a table is opened, CICS® builds’ it by extracting data from the tables corresponding source VSAM data‘’ set and loading it into an MVS™ data space owned by the CICS data tables server region, and constructing an index in CICS virtual storage above the 16MB line. The commands used to access these tables are the file control commands of the CICS application programming interface (API).

For information about defining CICS data tables, see the CICS Resource Definition Guide. For programming information about the file control commands of the application programming interface, see the CICS Application Programming Reference. CICS supports two types of data table :

For either type, a global user exit can be used to select which records from the source data set should be included in the data table.

For programming interface information about global user exits, see the CICS Customization Guide. For further information on CICS data tables, see the CICS Shared Data Tables Guide.

Opening data tables

A data table must be opened before its entries can be accessed by an application. You can open a data table explicitly with an OPEN request, implicitly on first reference, or by the CSFU task just after startup, if OPENTIME(STARTUP) was specified in the file definition. When a data table is opened, CICS reads the complete source data set, copying the records into a data space and building an index.

A global user exit can be invoked for each record copied into the data table. This copying is subject to any selection criteria of the user-written exit.

The commands used to open data tables, and the rules and options concerning their implicit and immediate opening are the same as those described in Opening VSAM or BDAM files.

Loading data tables

A data table is built automatically when it is opened. An index is constructed to provide rapid access to the records. See the CICS Shared Data Tables Guide for more details.

For a user-maintained data table, the ACB for the source data set is closed when loading has been completed. The data set is deallocated if it was originally dynamically allocated and there are no other ACBs open for it.

Closing data tables

You can close a data table with a CLOSE command, with or without the FORCE option. When a data table is closed, the data space storage that was used to hold the records and the address space storage used for the associated index, is freed as part of the CLOSE operation.

The commands used to close data tables, and the rules concerning current users of a data table are the same as those described in Closing VSAM or BDAM files.

XRF considerations

After an XRF takeover, a data table must be reloaded from its source data set when the data table is opened. For a CICS-maintained data table, the effect is to restore the data table to its final state in the previous active CICS region, because CICS keeps data tables and source data sets in step. For a user-maintained data table, the relationship of the current contents of the source data set to the contents of the data table when the previous active CICS region terminated is application-dependent.

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