You can concurrently access a shared sequential data set for output or update processing. In some cases, you can lose or destroy data when you update the data set, because one user could, at the same time, overwrite another user's updates.

The enhanced data integrity function prevents this type of data loss. This data integrity function either ends the program that is opening a sequential data set that is already opened for writing, or it writes only a warning message but allows the data set to open. Only sequential data sets can use the enhanced data integrity function.

Recommendation: The best way to identify applications that require data integrity processing is to activate it in warning mode. Then review the warning messages for the names of data sets that are identified. After you update the exclude list in the IFGPSEDI member with the data sets to be protected, consider activating data integrity processing in enforce mode.

Related reading: For more information on setting IFGPSEDI, see z/OS MVS Initialization and Tuning Reference.