I am guessing that you would do this something like shown below:
SELECT * FROM YourDB2Server.YourDB2Database.INFORMATION_SCHEMA.Tables
SELECT * FROM INFORMATION_SCHEMA.TablesHowever, I have not tried it, so there many be nuances that I am not aware of. Since INFORMATION_SCHEMA is an ANSI thing, I am guessing that it is available in DB2 as well. If not, you would need to do whatever is the equivalent of that in DB2.
The example above is for INFORMATION_SCHEMA.Tables. You could do a similar thing for INFORMATION_SCHEMA.columns