If SMS-managed data sets are being concatenated, then the system does additional processing for the transition between data sets. This includes additional checking of data set attributes. This might result in OPEN issuing an ABEND after successful completion of the OPEN that the user program issued. A violation of the like concatenation requirements could result in an ABEND during the open of the next concatenated data set.

If the open routine for QSAM obtains the buffer pool automatically, the data set transition process might free the buffer pool and obtain a new one for the next concatenated data set. The buffer address that GET returns is valid only until the next GET or FEOV macro runs. The transition process frees the buffer pool and obtains a new, system-created buffer pool during end-of-volume concatenation processing. The procedure does not free the buffer pool for the last concatenated data set unless you coded RMODE31=BUFF. You should also free the system-created buffer pool before you attempt to reopen the DCB, unless you coded RMODE31=BUFF.