Specifying logon modes when establishing a connection
When establishing a connection, IMS requires that session parameters define the rules a logical unit must follow when communicating with IMS. These session parameters are contained in the VTAM® mode table.
The use of the default logon mode table entry can be overridden in one of two ways:
- At system definition, the logon mode entry can be specified on the TERMINAL macro using the MODETBL=keyword or an ETO logon descriptor.
- The MODETBL keyword on the /OPNDST command can specify the logon mode table entry to replace the table entry defined at system definition.
- For information on specifying the MODETBL keyword, see IMS Version 15.4 System Definition.
- For information on specifying the /OPNDST command, see IMS Version 15.4 Commands, Volume 2: IMS Commands N-V.
If neither method is used to specify a logon mode table entry, VTAM uses the first entry in the default logon mode table, unless it is overridden by VTAM node mode table entry definition. If a logon mode table entry is specified, VTAM searches the default or user-specified logon mode table for the specified entry.
IMS examines the set of session parameters within the indicated VTAM mode table entry and overlays only those parameters on which IMS has dependencies. The remaining bytes are not changed. IMS ignores any unformatted user data transmitted with the session parameters.
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.