The terminal size message is irrelevant. You're seeing errors in the XS compilation. The README has some useful hints on building for various platforms (including Win32). The first thing I'd ensure is that you have the correct DB2 version:

        DB2 Application Development Client v7.2 or later
            Included with the DB2 Personal Developer's Edition and the
            DB2 Universal Developer's Edition
[download]

Note that the "or later" here might no longer be correct. You may have better luck reverting to an older version of DB2.

It's also worth noting that DBD::DB2 was last updated seven years ago, and has several unassigned issues, so you may unfortunately be somewhat on your own when it comes to debugging. I'm sorry I can't be of more direct help; I don't have easy access to a Win32 dev environment, nor the time needed to grok 25-year-old IBM C (again) :-)