DB2 for LUW 10.5 is not officially supported until the 7 series. This does not mean that it will not work, but that we have not done any official testing with DB2 LUW 10.5 on the 6 series. It is Pegasystems' policy not to backwards-test new versions of Platform Components with older releases. Support for new platform products is provided through newer versions of Pega software. If you choose to upgrade Platform Components to newer versions, but want to stay on older releases of Pega software, you may enter support requests for any problems encountered. However, if the root cause of these problems stems from the fact that the older versions of Pega were not designed to handle functionality in the newer Components, Pegasystems may request that you upgrade your Pega version to a release that directly supports that newer Component, as listed in the Platform Support Guide.
I was hoping to find a support request where we helped a customer who was running DB2 10.5 on 6.2 SP2, but I was not able to bring up anything with my initial searches.
If anyone else in the Product Support community has used this combination, please reply and let us know your experience!