Using DDIOCALC

You can use the DDIOCALC planning tool to try out allocation scenarios and see the effects. You can use it to determine which parameters to use and answer space questions, such as:

  • How much space do I need for x members?
  • How many members can I get into x space?

There are several ways to access the DDIO Calculator:

  • Menu selection on CSS Utilities Main Menu
  • Panel option on the File Facility Screen for both Source Listing and the Abend-AID Report.
  • TSO REXX Command DDIOCALC in SLCXEXEC
  • BMC AMI DevX Code Debug for TSO menu option 5.3

Related topics

Migrating-your-current-source-code-to-the-new-process

Compile and assembly JCL examples

When you open the DDIOCALC tool, the Primary Calculations Screen is displayed. If you have previously used the Primary Calculations Screen, it displays your previous entries.

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The DDIOCALC pulls in the input parameters directly from the file if you have a cataloged source database file.

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You are now ready to try out some changes.

Tip

Take a screenshot before starting.

To use this utility:

  1. Before making changes, clear the DSN and change the DIRX option to N.
  2. Make only one change at a time, and press Enter after each change.

First, we changed the Report Count to, 1000. The Report Count is the maximum number of members in the file.

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Notice that after we press Enter, the parameter we changed, turns green. Also, notice this change caused the Dir Blocks to increase to 56 and increased the percent full to 94.4.

Next, we changed the actual number of members to match the report count.

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This change caused DDIOCALC to calculate a new file size. At this stage, we being to get an idea of how much DASD space we need.

Next, we changed the CISIZE to the value that is more efficient in DASD utilization.

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Next, since we are using third-track blocking (CISIZE 18432), we changed the Group Count to a multiple of 3.

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To make DDIOCALC calculate the actual space required, clear the total cylinders, and press Enter.

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Now, you can apply this information in either creating your DBMODEL or reallocating your database.

 

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