You should be able to use the "include logs" option this way. The problem is that during the backup, DB2 might determine that it needs to include an archived log and thus needs to retrieve it. Like I said, I do not know tsm, but it might have a problem trying to retrieve a log file while it is backing up the same server. Using this method, it will try the retrieve from disk first, then tsm if that fails, although retrieving from disk almost never fails.
Andy