Hi,
when we do 'list applications', where the output data comes from. I mean, is there any table where the current applications info is stored and the command 'list applications' fetches the data from that particular table???

also for 'list active databases'.

Technically, there is no table that has that information, but DB2 V9.5 has some administrative views that will supply the information. Check out this view:

SYSIBMADM.APPLICATIONS

If you don't have version 9.5 you can use the following table function:

SNAP_GET_APPL_INFO

Go to the DB2 Info Center for your release and search on one of the above options to get more information on how they work.

If you have V9.5 the above view is preferred and I think the table functions will eventually be phased out.

I doin't think there is one for "list active databases" because the above view or function assumes you are connected to a database already (but not 100% certain about that).