General tips about performance when you use Z Data Tools functions

The following tips are provided as a guide to improving performance when using Z Data Tools functions:

Use the FASTREXX subset of REXX

If a user PROC is required, it is strongly recommended that, rather than the full REXX language, the FASTREXX subset of REXX is used. Z Data Tools provides a set of external REXX functions designed to allow many common tasks to be performed within the FASTREXX subset. See Z Data Tools User’s Guide and Reference Chapter 14, "Enhancing Z Data Tools processing" for a discussion of FASTREXX.

Template and copybook processing

The utilities DBX and DBI allow a copybook or template to be specified for the target/input data set, respectively. The utilities DBX, DBI, DBC, D2G, and DBP optionally require a Db2® template that describes the Db2® object to be processed. When using these functions, consider the following performance-related points:

• Z Data Tools can be most efficient if a template is used instead of a copybook. If a copybook must be used, specify the language of the copybook. (LANG=COBOL, LANG=HLASM, or LANG=PLI, instead of the default LANG=AUTO) for best performance.
• Template expressions should be written, if at all possible, using expressions suitable for Z Data Tools internal processing. For more details, see Z Data Tools User’s Guide and Reference "Improving performance using internal expression processing".