The LU 6.2 communications subsystem opens the Host Option for TCP/IP and initializes control blocks to interface with ACF/VTAM. When a client requests a connection to the remote DB2 location, it initializes a PLU of the DB2 LU 6.2 block and allocates a conversation with client-supplied information such as user ID, password and DB2 APPLID LU name.
This subsystem fills all necessary Function Management Header (FMH5) file information including LUWID. It transfers DDM flow to the remote DB2 location and receives messages from DB2. In case of an LU 6.2 communication error, the LU 6.2 communications subsystem formats an error packet and schedules a transmission request to the TCP/IP subtask.