Creating a partitioned data set

A PDS requires a different arrangement of space than a sequential data set. The PDS consists of two parts. One part contains the members. The other part is a directory of all the members and where they are located.

The steps for creating a PDS are the same as creating a sequential data set, except you specify space for the directory. After selecting the DATASET option (option 2) from the Utility Selection Menu, type A on the OPTION line and specify three data set qualifiers in the three ISPF LIBRARY fields. You don't name members at this time. You name members on the edit panel one at a time as you add them.

-------------------------------  DATA SET UTILITY  -----------------------------
OPTION ===> a

    A - Allocate new data set                 C - Catalog data set
    R - Rename entire data set                U - Uncatalog data set
    D - Delete entire data set                S - Data set information (short)
    blank - Data set information

ISPF LIBRARY:
    PROJECT ===>  prefix
    GROUP   ===>  memo
    TYPE    ===>  text

OTHER PARTITIONED OR SEQUENTIAL DATA SET:
    DATA SET NAME ===>
    VOLUME SERIAL ===>          (If not cataloged, required for option "C")

DATA SET PASSWORD ===>          (If password protected)

A PDS requires a different arrangement of space than a sequential data set. In the following example, notice that the DIRECTORY BLOCKS field has a value of 12. A sequential data set must have a value of 0 in this field. A general rule is to allow one directory block for every six members in a PDS.

----------------------------  ALLOCATE NEW DATA SET  ---------------------------
COMMAND ===>

DATA SET NAME:  PREFIX.MEMO.TEXT

   VOLUME SERIAL     ===>                (Blank for authorized default volume)*
   GENERIC UNIT      ===>                (Generic group name or unit address)*
   SPACE UNITS       ===> blks           (BLKS, TRKS or CYLS)
   PRIMARY QUAN      ===> 50             (in above units)
   SECONDARY QUAN    ===> 20             (in above units)
   DIRECTORY BLOCKS  ===> 12             (0 for sequential data set)
   RECORD FORMAT     ===> VB
   RECORD LENGTH     ===> 255
   BLOCK SIZE        ===> 5100
   EXPIRATION DATE   ===>                (YY/MM/DD
                                          YY.DDD in Julian form
                                          DDDD for retention period in days
                                          or blank)


   ( * Only one of these fields may be specified)

The previous panel shows an example of values for a PDS. However, you might want to find out the values your installation recommends.

To review what the allocate fields represent, see Allocate New Data Set of Creating a sequential data set. For more information about these fields, press the HELP PF key (PF 1) while the Allocate New Data Set panel is displayed, or see z/OS TSO/E User's Guide.

Exercise
Create a PDS named PREFIX.MEMO.TEXT following the example starting at Creating a partitioned data set. Be sure to change the DIRECTORY BLOCK field from 0 (for a sequential data set) to a number greater than 0. When you press the Enter key on the last panel, your data set is created and you see the message: `DATA SET ALLOCATED`