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Understanding the methods of VTAM AutoLogon session initialization

You can issue a START command at the operator’s console or customize START commands to your system configuration.

The following ways are available for issuing a START command to initialize a VTAM AutoLogon session:

  • Automation or scheduling product

    A START command that is configured to an automation or scheduling product typically can be up to 256 character spaces, depending on the product.

    See your automation or scheduling product documentation for more information.

  • Operator command 

    The operator-entered START command string can be up to 121 character spaces in length.

    If you cannot fit all of the required parameters for your VTAM session onto the operator command line, perform the following steps:

    1. Define a BBVTASxx member (see Defining other LAS and TAS initialization parameter lists) to contain the LOGON command and parameters.
    2. Point to this member in the START command by using the SUF keyword (see Defining the START command for VTAM AutoLogon sessions for more information).

  • IPL procedure 

    Sixty-five bytes are provided for a START command in an IPL procedure, such as the COMMNDxx member of SYS1.PARMLIB.

    You must use the SUF keyword that points to a BBVTASxx member in a START command configured to your system’s IPL procedure. (See Defining the START command for VTAM AutoLogon sessions for more information about using the START command and the SUF keyword; see Defining BBVTASxx members for VTAM AutoLogon sessions for more information about defining BBVTASxx members.)

    If you want to include VTAM AutoLogon sessions in your IPL procedure, consider that VTAM can take a long time to initialize at IPL and might not be fully operational by the time a TAS attempts to initialize. If VTAM is not available, the TAS does not initialize.

    Likewise, a session cannot become active unless the VTAM major node is active. You can configure the VTAM application major node name to be activated automatically at VTAM startup by adding the major node name to SYS1.VTAMLST member ATTCONxx.

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