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Controlling TAS initialization parameters

The following locations are available to define TAS parameters for AutoLogon sessions:

At TAS initialization, MainView Alternate Access reads parameters from all the locations in a specific sequence

  1. Parameter list member
  2. Procedure JCL
  3. START command

As each location is read in sequence, all parameters are merged. Duplicate values are overwritten as the merging sequence progresses. Default values are substituted for required parameters that are not defined or are invalid.


If invalid parameter values are encountered during the merging sequence, initialization continues, using default values, and messages are issued. These messages specify which values or parameters are invalid.

Duplicate values can occur only when the START command contains one or both of its keyword parameters. The keyword parameters that are supported in the TAS START command are SUF and P (see Defining the START command for VTAM AutoLogon sessions for more information). These keywords provide different methods of starting AutoLogon TASs.

The keywords are defined to the PROC statement in the TAS procedure (default of BBVTAS) and symbolic equivalents to the PARM parameter of the BBVTAS EXEC statement. These keywords can be used separately or together with the START command, as described in Defining the START command for VTAM AutoLogon sessions.

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