In most cases, changes to recoverable data sets made by a transaction remain invisible to other transactions until the modifying transaction reaches the commit. However, if you are using the no-read integrity (NRI) option, you might see uncommitted changes. Exclusive locks that VSAM RLS holds on the modified records cause other transactions that have read-with-integrity requests and write requests for these records to wait. After the modifying transaction is committed or backed out, VSAM RLS releases the locks and the other transactions can access the records.

The CICS® backout function removes changes made to the recoverable data sets by a transaction. When a transaction abnormally ends, CICS performs a backout implicitly.

The commit and backout functions protect an individual transaction from changes that other transactions make to a recoverable data set (or other recoverable resource).