You create connection definitions using the Open ClientConnect utilities.
For LU 6.2, use SYMS and SYMC transactions.
For TCP/IP, use SYGWHOSTS in Open Client Customization module.
In the Customization Module (SYCTCUST,
a JCL member) there is a default protocol field for IBM TCP/IP,
Interlink TCP/IP, LU 6.2 and CPIC.