Application programming for user-maintained data tables

If a request cannot be satisfied from a user-maintained data table, CICS® does not access the source data set (as it would for a CICS-maintained data table); instead it returns an exceptional-condition response.

Records that were in the source data set when the data table was opened might be absent from the data table because they were not copied during loading. This could be due to suppression by the user exit XDTRD or some abnormal event such as the data table becoming full.

Some application programming requests are not supported for a user-maintained data table. They include, for example, read requests that use the UPDATE option with an imprecise key. You might need to change existing applications to avoid these requests or to handle the exceptional conditions returned by CICS. For more information, see Application programming for a user-maintained data table.

You can use the user exits in data table services to put only the records that you need to access in the data table; there is no possibility of the source data set being accessed for those that you do not load.

You can also use the user exit XDTRD to modify each record (by selecting, for example, only a subset of its fields) when it is loaded.

Related concepts
Application programming for a user-maintained data table
User-maintained data tables
Resource definition for user-maintained data tables
Operations with user-maintained data tables
CICS-maintained data tables
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