Space allocation for a PDSE is different from a PDS. To allocate a PDSE, specify LIBRARY in the DSNTYPE parameter.

This topic shows how to use the SPACE JCL keyword to allocate primary and secondary storage space amounts for a PDSE. The PDSE directory can extend into secondary space. A PDSE can have a maximum of 123 extents. A PDSE cannot extend beyond one volume. Note that a fragmented volume might use up extents more quickly because you get less space with each extent. With a SPACE=(CYL,(1,1,1)) specification, the data set can extend to 123 cylinders (if space is available).

Because PDSE directory space is allocated dynamically, you do not need to estimate the number of PDSE members to be created. Therefore, the directory block quantity that you specify on the SPACE keyword is not used for PDSEs, but is saved and available for use by conversion utilities. Alternately, you can omit the directory quantity by specifying DSORG=PO in your JCL DD statement or the data class when allocating the data set.