What is the difference between CLSDST=PASS and ACCESS=PASS?

Document ID : KB000050084
Last Modified Date : 14/02/2018
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PASS has different meanings when used with CLSDST and ACCESS. CLSDST PASS is not the same as ACCESS PASS.


  • CLSDST(PASS) is a VTAM function.

    • A back-end system can end a network session with a VTAM CLSDST(PASS) request. This indicates that the back-end will reestablish a session with the front-end by using a different PLU name (a third-party PLU). The front-end system detects reestablishment of the session by receiving an unsolicited bind request; therefore, when the back-end system ends a session, it is important for it to indicate that an unsolicited bind is to be expected.

    • The "CLSDST PASS" approach: Generally speaking, an end user desiring to use a VTAM application logs on instead to a special session manager VTAM application that displays a menu of available VTAM applications. When the user selects an item from the menu, the session manager application issues a CLSDST PASS macro instruction followed by a SIMLOGON to VTAM to cause VTAM to terminate the end user's session with the session manager and to pass the end user to a new session with the VTAM application selected from the menu. This approach has the advantages including simplicity and low overhead, and it provides some user flexibility in logging on to other VTAM applications, but it also has disadvantages including permitting only one session at a time.

  • ACCESS a TPX parameter.

    • This defines the type of access to applications. PASS is one type of access.

These two parameters are referenced at various places within TPX Administration (TPXADMIN) System Options:

ACT (Application Characteristics Table):

Issues CLSDST PASS - Indicates whether the application may issue a CLSDST PASS to another VTAM applid after the initial session to this application is established. Specifying Y allows TPX to recognize that the aspects of CLSDST PASS processing are normal and not error situations. If you specify Y and the application type is GRP, you normally need to specify a substring so TPX can identify the original application session.

SMRT (System Options Table):

ACCESS - The access mode defines the type of access to applications:

  • MULTIPLE access allows users to activate more than one application at a time.

  • SINGLE access allows users to sign on to only one application, but still have access to other functions.

  • PASS access passes control of the terminal to the application and a user cannot access the software while the session is active. You can use PASS for file transfers.

    • PASS provides the user with a simplified mode of access to applications. The user receives the Menu at signon. After the user activates a session, the product passes control of the physical terminal to the application, and the user cannot access the Menu or any other features while the application session is active.

    • You cannot use PASS mode when using the TCPaccess Telnet Server interface.

A user administrator can specify a lower, but never higher, level of ACCESS in a profile or user definition.

Session Options (Profile or User):

ACCESS=PASS indicates that this session should be treated as ACCESS=PASS even though the system or the user has ACCESS=SINGLE or ACCESS=MULTIPLE.

ACCESS changes the user's session access privileges from that specified in the SMRT:

  • SINGLE restricts the user from having more than one session at a time.
  • PASS restricts the user to having passed sessions only.