This is a forum of volunteers. There were five hours between your original post and follow-up.
If you seek official answers from Oracle, then the course of action is to open a SR with them. If you seek assistance from random people who usually enjoy working with Oracle, then this is the place.
As this is an Oracle based forum, you will need to provide details on what formats DB2 can export the desired data into. Last time I touched DB2 was over 10 years ago. I would guess you will end up going a simple text file method to transfer between the two, but that is making an assumption that there is no way for the two systems to communicate directly.
What are you loading the XML into in 11.2.0.x? How about data volume or XML size?
There are plenty of examples for loading XML from flat files into the DB. Whether that is really the best approach for you depends upon a lot of things we don't know.