You should not use PDSEs if your application expects short blocks before the end of a member. You can create short blocks for PDSE members, but their block boundaries are not saved when the data set is written. For example, if you use the TRUNC macro with QSAM to create short blocks, the short blocks are not shown when the data set is read. If the QSAM TRUNC macro is used, a message is written to the job log and an indicator is set in the SMF record type 15. A BSAM or BPAM TRUNC macro does not have this effect.