Resolution:
S6BCSCLI is used to provide CICS services to Remote CLI sessions running within an Object Service Broker CICS Execution Environment (EE).

CICS services would include services such as VSAM file support and CICS external routines. If you use the Windows based Eclipse User Interface (UI) and connect into a CICS EE, you will need to define the following resources to CICS:
1) TRANSACTION(HCLI) calling PROGRAM(S6BCSCLI)
2) PROGRAM(S6BCSCLI) as RESIDENT(YES)

Remote CLI sessions are created using the TIBCO Object Service Broker SDK client which is an extension of the Call Level Interface. The SDK client extends the interface beyond the boundaries of the Execution Environment address space. Any communications protocol supported by TIBCO Object Service Broker can be used although Remote CLI sessions are usually connected to the CICS EE through the TCP/IP Relay component of Object Service Broker and never through CICS Terminal Control. Although the Eclipse UI uses this interface, you can write your own SDK interface using the SDK client.

Environment:
  Using Remote CLI interface to connect to a z/OS CICS Execution Environment (EE).

TIBCO Products:  
  TIBCO Object Service Broker for z/OS
  TIBCO Service Gateway for CICS

Operating System(s):
   z/OS

Third party software:
  CICS Transaction Server for z/OS

References:

For additional information on configuring a CICS Transaction Server for z/OS address space to support Remote CLI clients, review:
1) TIBCO® Object Service Broker for z/OS External Environments Software Release 5.0. This manual contains directions on how to configure a CICS EE to support Remote CLI clients (those using the SDK interface). See Chapter 18, section "Additional Requirements for CICS Execution Environments".
2) TIBCO® Object Service Broker for z/OS  Installing and Operating Software Release 5.0 for general information about installing and customizing the TIBCO Service Gateway for CICS component and TCP/IP Relay communications.
3) the IBM library for the particular release of CICS Transaction Server for z/OS that you are using.

Is program S6BCSCLI a required CICS definition for Object Service Broker?