Joined: 07 Nov 2005 Posts: 1105 Location: The Netherlands at Hole 19
This is what the fine manual states:
Two or more data sets can be retrieved by the system and processed successively as a single sequential data set. This is called sequential concatenation. With sequential concatenation, the application program treats a collection of data sets as one sequential data set. The number of data sets that you can concatenate with sequential concatenation is variable. It is governed by the maximum size of the TIOT option. The system programmer controls the TIOT size with the option ALLOCxx member of SYS1.PARMLIB. See z/OS Initialization and Tuning Reference. When data sets are sequentially concatenated, the system is open to only one of the data sets at a time. Concatenated data sets cannot be read backward. During sequential concatenation, the system treats a member of a PDSE or PDS as if it were a sequential data set. The system treats a striped extended format data set as if it were a single-volume data set.