If you have multiple TCP/IP stacks and need to use one other than the default, add a step to the JCL of the VP390 started task to run the IBM program BPXTCAFF which can be used to set the desired stack name. Add this step before one running the Ironstream agent.
Example:
//SETSTACK EXEC PGM=BPXTCAFF,PARM=<stackname>