The program development process for DB2 necessitates a good understanding of the use of Packages, Plans, Collections, and package versions. A very good Redbook that was written for DB2 Version 9, does a very good job of describing these components. Its title is ‘Packages Revisited’ - Document # SG24-7688. The current link is to the manual is here -

Package versioning introduces an interesting challenge to the DBM support group, as it allows programmers to included an unlimited number of versions for their packages. This inevitably results in a large number of, sometimes obsolete packages, that populate the catalog tables and has put a need for a housekeeping effort to manage the package versions.

With the agreement of development DBA’s we have a process that cleans up old versions of DB2 packages, with a limit of 1 for DBT, and 2 for all other subsystems. This means that when the housekeeping process runs, only the most recent 1 or 2 package versions are kept, and older versions are deleted.