Using the DSRSEXIT user exit to add SMS classes
If no SMS classes (DATACLAS, MGMTCLAS, and STORCLAS) exist in the DSNZPARMs or storage-group definition, you can add the classes by using the DSRSEXIT user exit.
However, you cannot change existing specified SMS classes by using the DSRSEXIT user exit. REORG PLUS ignores values that you specify for a class in the DSRSEXIT user exit if a value already exists for that class. REORG PLUS truncates values that exceed eight characters.
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