Upgrade Guide for DB2 UDB for z/OS and OS/390 > Database and UI Upgrade Planning > Planning Your Upgrade >

Capacity Planning

For recovery purposes, an in-place upgrade is not supported on the zSeries host. If you want to keep both source and target databases, you must plan for additional disk space.

Verify that you have enough space on the zSeries host to allow for the unloading of datasets. Typically, you need at least 200 cylinders of space.