Required message queue (key queue key ) already exists, will not reuse
A CICS® Transaction Gateway component tried to create an Operating System message queue that already exists. The queue key is queue key and is based on the process ID (PID) of the component. This will be the Gateway daemon PID or Client daemon PID.
The message is written to the client log and if the component affected is the Client daemon, it fails to start. Requests to servers connected by TCP/IP or SNA will fail.
Shut down the Gateway daemon and Client daemon, and restart the CICS Transaction Gateway.