Establishing connection and specifying logon modes

When establishing connection using the VTAM® OPNDST macro instruction, IMS specifies session parameters that define the rules that a logical unit must follow when communicating with IMS.

IMS examines either a user-supplied or a VTAM default set of session parameters, and overlays only those parameters on which IMS has dependencies. The remaining bytes are not changed. You can include user data with the BIND parameters.

User data included within the BIND is used by IMS as input to the signon process and is similar in function to the IMS /SIGN command. This is required for ETO Finance terminals and SLU P terminals, but is optional for static terminals.

If you do not specify a mode name on the TERMINAL macro statement during IMS system definition or on the logon descriptor, you can supply a mode name using any of the following methods:

  • On the VTAM network operator VARY command
  • On the IMS OPNDST command
  • On a request for system initialization by another logical unit

If you specify a mode name on the IMS TERMINAL macro statement or on the logon descriptor, it is used, unless you override it using the IMS /OPNDST command or the VTAM VARY command.

If you do not supply a mode name during IMS system definition using a logon descriptor, on an IMS command, or using CINIT, VTAM assumes a default mode name.

Related reading: For more information on establishing logon mode tables and defining logon mode table entries, see z/OS® Communications Server: SNA Resource Definition Reference.

You can override the use of the default logon mode table entry in one of two ways:

  • At system definition, you can specify the logon mode entry on the TERMINAL macro using MODETBL= keyword.
  • You can specify on the MODETBL keyword of the /OPNDST command that the logon mode table entry replace the table entry defined at system definition.

IMS overrides the session parameters for function management, transmission services, and primary and secondary network protocol.