Allocating a DDIO file

This section contains the formulas for allocating a DDIO file. After you have allocated a temporary file using the sample installation library members, use the following information to calculate the permanent DDIO file. Refer to Selecting a File Access Method before allocating the file.

1. Calculate the average member size in KBs.
   You can calculate the average member size in KBs using the DDIO file with the default 4500 4 KB block allocation and the DIRX report. Refer to the DIRX report for the average member size (in groups).

   Use the following formula:

   AVERAGE MEMBER SIZE (IN GROUPS) x GROUPCOUNT x BLOCKSIZE/1024 =
       average member size in KBs

   Refer to the following DIRX report for the necessary information to complete the calculation.

   DIRXINDD=ABNLFROM
   DSN ............................. CX.QA.DDIO.SC.ADNO
   VOLSER .......................... PRD903
   AM(ACCESSMETHOD) ............... VSAM
   BLKSIZE ......................... 4089
   TYPE ............................ SOURCE
   REPTCOUNT ....................... 200
   GROUPCOUNT ...................... 9
    ....
   MEMBERSUMMARYOFCX.QA.DDIO.SC.ADNO
   NO OF MEMBERS ................................ 12
   NO OF LOCKED MEMBERS......................... 2
   NO OF UNLOCKED MEMBERS ....................... 10
   NO OF INCOMPLETE MEMBERS ..................... 0
   LARGEST MEMBER SIZE  (INGROUPS) .............. 5
   SMALLEST MEMBER SIZE (INGROUPS) ............. 4
   AVERAGE MEMBER SIZE (INGROUPS) .............. 4.5
   SPACE SUMMARY BASED ON AUTO DELETE=STAGED
   MAXIMUM ALLOCATION GROUPS .................... 896
   AVAILABLE ALLOCATION GROUPS .................. 892
   MAXIMUM NO OF DIRECTORY ENTRIES (REPTCOUNT) .. 200
   AVAILABLE NO OF DIRECTORY ENTRIES ............ 188
   ENTER UTILITY COMMAND:
   ***ALLFUNCTIONS SUCCESSFULLY COMPLETED.

   Tip

   The DIRX report for BMC AMI DevX Abend-AID for CICS does not show the member size for specific members. You can calculate the size of a specific member by multiplying the number of EXTENTS by the GROUPCOUNT. Then multiply that number by the BLOCKSIZE to determine the member size in bytes.

2. Calculate the DDIO file size.
   After determining the average member size in KBs, use the following formula to determine the number of bytes required for the entire DDIO file:

   average member size in KBs x estimated number of file members =
       DDIO file size in KBs

3. Calculate the allocation in blocks.
   Next, determine the number of blocks the DDIO file will use by dividing the total number of bytes required for the file by the block size.

   file size (determined in Step 2) x 1024/BLOCKSIZE = number of blocks