The process of logging on to CICS using autoinstall

To help you understand the process, consider what takes place when you log on to CICS® through VTAM. (The process is illustrated in Figure 1 and Figure 2.) CICS supports the model terminal support (MTS) function of VTAM 3.3 and above. Using MTS, you can define the model name, the printer (PRINTER), and the alternate printer (ALTPRINTER) for each terminal in a VTAM table. CICS captures this information as part of autoinstall processing at logon, and uses it to create a TCTTE for the terminal. If you are using MTS, you must use a version of DFHZATDX that is suitable for use on CICS Transaction Server for z/OS®. See CICS Customization Guide for programming information about the user-replaceable autoinstall program.
  1. VTAM receives your request, determines that you want to use CICS, and passes your request to CICS.
  2. CICS extracts your terminal's NETNAME name from the logon data. CICS searches the TCT for an entry with the same NETNAME.
  3. If it finds such an entry, CICS issues an OPNDST to VTAM to establish a session between CICS and the terminal. This is the normal CICS logon process.
  4. If it fails to find a matching entry, CICS checks the system initialization parameters that were specified in the SIT, or reset using CEMT, to check whether it can allow an autoinstall.
  5. If the system initialization parameters allow an autoinstall, CICS checks the terminal data passed by VTAM, to check whether the terminal is eligible for autoinstall.
  6. If the terminal is eligible, CICS examines the bind image to see if it carries sufficient information.
  7. If the VTAM bind image data proves sufficient, CICS searches the autoinstall model table (AMT) in sorted ascending order, and autoinstalls the terminal in one of the following ways:
    • If VTAM has supplied CICS with a valid model name, CICS passes this name to the autoinstall control program. (If the logon request has come to CICS through VTAM 3.3, and if you have supplied VTAM with names of model terminals, CICS can obtain the name of the model terminal from the logon data.)
    • If VTAM has not supplied CICS with a valid model name, CICS searches the AMT for suitable autoinstall models and passes these to an autoinstall control program, together with VTAM logon data. If VTAM has supplied CICS with an invalid model name, message DFHZC6936 results.
  8. The autoinstall control program (either the CICS-supplied program or one written by you) selects one of the models and provides the rest of the information necessary to complete a TCT entry for the terminal.
  9. When the autoinstall control program returns control, CICS builds a TCT entry using the autoinstall model, the data returned by the autoinstall control program, and the VTAM logon data for the terminal. CICS then adds the new entry to the TCT and issues an OPNDST to VTAM to establish a session between CICS and the terminal.
  10. If the TYPETERM definition so specifies, CICS uses the QUERY function to find out about some of the features of the terminal. (These features are listed in TYPETERM resource definitions.)
Figure 1. The process of logging on to CICS using autoinstall.

Note that the autoinstall process itself is shown as a single box. What happens inside this box is depicted in Figure 2

This figure illustrates the process of logging on to CICS using autoinstall, which is described in the text.
Figure 2. How CICS autoinstalls a terminal.

Note that the overall process in which this fits is shown in Figure 1

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This figure illustrates how CICS autoinstalls a terminal, and is described in the text..