The DDM listener program runs in a batch job. There is a one-to-many relationship between it and the actual server jobs; there is one listener and potentially many DDM server jobs. The server jobs are normally prestart jobs. The listener job runs in the QSYSWRK subsystem.
The DDM listener allows client applications to establish TCP/IP connections with an associated server job by handling and routing inbound connection requests. After the client has established communications with the server job, there is no further association between the client and the listener for the duration of that connection.
The DDM listener must be active in order for DRDA® Application Requesters and DDM source systems to establish connections with the DDM TCP/IP server. You can request that the DRDA listener be started automatically by either using the Change DDM TCP/IP Attributes (CHGDDMTCPA) command or through iSeries™ Navigator. From iSeries Navigator, navigate to the DDM settings: . This will cause the listener to be started when TCP/IP is started. When starting the DRDA listener, both the QSYSWRK subsystem and TCP/IP must be active.