The theme says it all. Looking at sql capture introduced in DB2.
Take a look at the Exeries SQL output points that let you log any submitted SQL. The only problem is that you have to write your own logging programs:
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/index.jsp?topic=%2Frzaik%2Frzaikodbcexitprog.htm
If you have Java support enabled, you can use Profiler SQL PL.
http://www.ibm.com/developerworks/data/library/techarticle/dm-0406rielau/index.html
I am using the DB2 command center with a graphical representation of the generated tree
ISeries Navigator has SQL Performance Monitor. I could never understand this, but it may be what you are looking for.