Removing Observability

Observability involves the kinds of data that can be stored with an object, and that allow the object to be changed without recompiling the source. The addition of this data increases the size of the object. Consequently, you may want to remove the data in order to reduce object size. But once the data is removed, observability is also removed. You must recompile the source and recreate the program to replace the data. The types of data are:

Create Data

Represented by the *CRTDTA value. This data is necessary to translate the code to machine instructions. The object must have this data before you can change the optimization level.

Debug Data

Represented by the *DBGDTA value. This data is necessary to allow an object to be debugged.

Profiling Data

Represented by the *BLKORD and *PRCORD values. This data is necessary to allow the system to re-apply block order and procedure order profiling data.

Use the CHGPGM command or the CHGMOD command to remove some or all the data from a program or module respectively. Removing all observability reduces an object to its minimum size (without compression). It is not possible to change the object in any way unless you re-create it. Therefore, ensure that you have all source required to create the program or have a comparable program object with CRTDATA. To re-create it, you must have authorization to access the source code.