How Virtual Terminals are determined by TPX.

Document ID : KB000054901
Last Modified Date : 14/02/2018
Show Technical Document Details


How Virtual Terminals are selected by TPX?


The ACT table APPLID (application) definition in TPXADMIN specifies the virtual terminal TYPE that is to be targeted when a session to the APPID is selected. However, if the APPLID is not defined in the ACT table, then TPX will assume defaults for the applid/application, and one of the defaults is to target UNIQUE virtual terminals for use by this applid/application.

So how does TPX select a virtual terminal?

When you sign on to TPX, you do so with a physical terminal, where the information about that physical terminal is displayed on the TPXMENU (upper, right of panel display). In most instances, when a session to an application is first selected, TPX determines the virtual terminal TYPE by checking to see if the APPLID for the session is defined in the ACT table-APPLID definition; if so, the TYPE=SHR/GRP/UNQ determines the target virtual pool, otherwise, the default UNQ virtual terminal pool is the target pool.

TPX next starts at the TOP of the virtual terminal node/pool definitions, walks thru the terminal definitions, and tries to find a virtual terminal that 1) is defined in the target pool (i.e. correct TYPE) and 2) does not already have a session (if target pool is UNQ) or a session to the applid (if target pool is GRP) on the virtual terminal. TPX will then use the BIND from the physical terminal to send over the virtual terminal; thus, if you log on to TPX as a MOD4, then most of your sessions to various applications will also be as a MOD4. In effect, the DLOGMOD (DLOGMOD=xxxxxxxx) definition in each virtual terminal is ignored/not queried.

However, the exception to this is as follows:

  1. If the ACT table-applid definition/fields: MODEL SENSITIVE = Y, EXTENDED
    DATASTREAM = Y., and/or MODE ENTRY OVERRIDE is set to a logmode value
    (i.e. not underscores).

  2. If the PROFILE level session detail and/or USERID level session detail has a MODENT name value specified (override to ACT-applid MODE ENTRY OVERRIDE field)

Any of the above noted fields will cause TPX to query the DLOGMOD field in each virtual terminal definition in order to find a match, and the virtual terminal node needs to have the correct number of MODELs 2/3/4/5/E defined.