Directory block records

The directory records are written immediately after the header records. They consist of directory blocks containing the original directory entries for all members to be unloaded. In addition, the last directory record contains an end-of-file block.

The length of each directory record, except the last one, is 8 + n(276), where n represents the blocking factor (n is an integer greater than zero). The length of the last directory record is 8 + n(276) &plus 12, where n represents the blocking factor (which may be zero).

The directory blocks in the figure contain a count, key, and data field. The count field is set to zero, except for the key length (X'08') and the data length (X'0100').

Figure 1 gives the directory record format for the unloaded partitioned data set. The following items have been assumed:

The block size of the data set to contain the unloaded data set is 900 bytes.
Seven pseudo directory blocks are required to contain the original directory entries for all of the unloaded members.

Related reading: For more information about directory blocks, see z/OS DFSMS Using Data Sets .

Figure 1. Directory Record Layout