we had a porblem with the SQLCODE of -842 (connection already exists), while working on DRDA calls. Not sure why this error occurred. even we tried doing a reset before making a connection to remote machine.
we were able to find out the problem and correct it. Actually our program was using aliases pointing to other production boxes. so we removed those aliases and did a remote connection to those boxes and retrieve data.
And the problem came because we missed a subprogram(that was using alias) which was called before the changed subprograms and so the next subprogram that was doing a remote connection abended with -842 sql code(connection already exists).
We changed the leftout subprogram to do a remote connection, and the job was done .