| Note: | Setting and removing the EXTENDED attribute for existing data sets require a record format reorganization. |
The EXTENDED data set attribute, when set to TRUE, causes the data set to have records that contain two additional words at the beginning of the record:
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A Record Serial Number (RSN) field containing a unique data set number that is used as a duplicate set tiebreaker.
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An internal Transtamp field whose value allows an unlimited number of locked records among XE data sets and speeds up database availability during halt/load recovery if the EXTENDED attribute is set for all data sets. Although there is no create or lock limit for XE structures per transaction, if a transaction involving the creation of many records (approximately 200,000 or more) aborts, SINGLEABORT can fail. If SINGLEABORT fails, a halt/load recovery will successfully recover the database.
User programs require no modification when EXTENDED is set, but they do require recompilation. User programs can be modified to access the RSN provided that the RSN has been explicitly declared in the DASDL.
If not specified, the EXTENDED attribute is FALSE by default. The EXTENDED attribute default value can be overridden at the data set level.
If the database is audited and the EXTENDED attribute is set to TRUE for at least one structure, then the INDEPENDENTTRANS database option must also be specified.
If the database is unaudited, the EXTENDED attribute can be set to TRUE, but the INDEPENDENTTRANS database option must not be set.
Both setting and removing the EXTENDED attribute for existing data sets require a record format reorganization.
Be sure to take in account the explicit or implicit setting of EXTENDED when calculating data set BLOCKSIZE specifications.
An embedded data set and its owner data set must have the same value set for the EXTENDED attribute.
Sets and subsets that span an XE data set implicitly have the EXTENDED default set to TRUE.
The EXTENDED attribute is not allowed for the restart data set.
