from developerworks:
"1) In the DBM Configuration (The instance-level parameters) under "Communications,", there is a parameter called SVCENAME. Mine was initially blank. In it I put 50000 (the default DB2 port number). I then issued a DB2STOP and DB2START (or right click on the instance icon in Control Center, choose stop, and then after stopped successfully, choose start the same way.) I then noticed that the prebuilt database connections in Data Studio no longer had a port of -1 but had a port of 50000 (the correct one).
However, this did not prove to correct everything. It still was issuing "connection refused" errors with the sqlcode and sqlstate mentioned earlier. I had to therefore perform one more task:
2) Click once again on the instance icon in the navigation tree of Control Center. The detail pane (at the lower right) now contains information about your instance (DB2 in my case). There should be three actions, Configure Parameters, Setup Communications, and Add New Instance. Click on Setup Communications. You should then get a dialog box. Mine had three possible checkboxes, NetBIOS, TCP/IP, and NPIPE. All three were unchecked. To get mine running I checked TCP/IP, then clicked on the Properties button. It showed a Host Name with my PC name, a blank Service Name, and a Port Number of 50000. I left everything as it was and clicked cancel, and then clicked OK for the main communications dialog. Then I stopped and restarted the instance again (as in step 1), and tried my prebuilt connections in Data Studio. They all worked at that point.
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