Before the start of most projects, especially those effecting an entire application, it's good to know what programs are your responsibility.  It's no fun finding programs you missed because they're run "on demand" at end-of-year, but are not officially "in production."  It's also nice to eliminate unused programs written as a one-time conversion, or fix, that are no longer needed.

Inventory will create a list of the executable programs that comprise a data processing application.  It uses the JOB, PROC, LOAD, and Source libraries to obtain the initial program list.  It uses this list to analyze each programs static and dynamic CALLs, which will determine any other affected source code.  Once the program members have been defined, all of the COPY members they reference are also examined, as are the programs that contain references to CICS, IMS/IDMS, or SQL processing.

Once the inventory is completed, you know exactly which programs and JCL encompass an application, which are in use, and which are no longer used.  This eliminates unnecessary processing of unused job streams, and obsolete programs and COPY members.  Now, with this inventory, you have the basis to begin any project, big or small.