Network communication function (CB)

The network communication function (CB) subtask supports the transmission of data between the controlling system and controlled systems. This data can be events, JCL, commands, or WTO messages. This subtask provides services for:

• Session establishment
• Session termination
• Subsystem stop
• Queued event-record handling
• SEND processing
• RECEIVE processing.

CB subtask initialization consists of:

• Building the internal control blocks (NAB and SCBs)
• Building the VTAM® control blocks (ACB, NIB, RPLs, and EXLST)
• Processing initialization parameters
• Building ECB and associated events lists
• Opening the ACB
• Issuing the SETLOGON macro to allow logons.

VTAM® exit modules include:

• The LOGON exit
• The VTAM® SCIP exit
• Completion exits
• The VTAM® LOSTERM exit
• The VTAM® TPEND exit
• The VTAM® NSEXIT exit.