i know its too late to reply as you might have got a solution already.
In you statement, you say you write to another table.
you Cursor must be fine if it is readonly cursor, but what about your other query that inserts or updates. The CS releases the lock on page only if its has not been updated, else it locks it till commit. So if now your cursor is updateable, you run a potential risk of locking all rows(or pages) your cursor has updated, even if isolation is CS.
the next thing you need to look at is the LOCKSIZE Parm in the tablespace create DDL. if its not PAGE (which is most of the time), your DBA is right.
Do let me know what you did finally