Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Migration Guide

Make application program updates

The following application programming tasks are necessary when converting your source. You must decide what size your program updates will be. For example, you can choose to update programs along with your regular maintenance, or you can divide your programs into functional groups and update the source group by group. Some customers have followed the ’big bang’ process and have made all their program updates at once. However you decide to proceed, these tasks should be performed in roughly the following order:

Save the existing source as a back-up—a benchmark to compare to and a version to recover to—if the converted modules have problems.

  1. Update the job and module documentation.

    It is extremely important that all updates be properly documented. PL/I itself is reasonably self-documenting. However, keep a log of the compiler options you specify and the reasons for specifying them. Also document any special system considerations. This is an iterative process and should be performed throughout the conversion programming task.

  2. Update the available source code.

    Update the source code manually or with tools that you have developed. For information on when source code must or may need to be changed, see Understanding when working code must be changed and Understanding when working code may need to be changed.

  3. Compile, link-edit, and run.

    After the source has been updated, you can process the program as you would a newly written Enterprise PL/I program. ( You need the Language Environment run time installed.) If, during the compile process, you see new messages and wish to understand them better, see Understanding the new compiler's messages.

  4. Debug.

    Analyze program output and, if the results are not correct, use Debug Tool or Language Environment dump output to uncover any errors.

  5. Test the converted programs.

    After moving your source to Enterprise PL/I, set up a procedure for regression testing. Regression testing will help to identify:

    After you have established a regression testing procedure, and after your programs run correctly, test them against a variety of data:

    In this way, you can exercise all the program processing features to help ensure that there are no unexpected execution differences.

    The importance of regression testing cannot be stressed enough. You should consider the move from an ’old’ PL/I compiler to Enterprise PL/I as a move to a different, though similar, language and plan your testing accordingly.

  6. Repeat when necessary.

    Make any further corrections that you need, and then recompile, relink, rerun, and, if necessary, continue to debug.

  7. Cut over to production mode.

    When your testing shows that the entire application receives the expected results, you can move the entire unit over to production mode. (This assumes your production system is already using the Language Environment run time. If not, STEPLIB to the Language Environment run time. See STEPLIB.)

    In case of unexpected errors, be prepared for recovery:

  8. Run in production mode.

    After cut over, monitor the application for a short time to ensure that you are getting the results expected. After that, your source conversion task is completed.


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