IBM Session Manager Implementation

Chapter 1. Session Manager overview 47

1.6 Application sessions

Once a terminal is signed onto Session Manager, up to 999 different sessions

may be activated from that terminal. Session Manager does this by simulating a

terminal for each session using a VTAM Access Control Block (ACB) or a TCP/IP

connection. Once the session is established, the application behaves as if it is

writing to a physical device, but in fact it is communicating with the terminal via

the ACB or TCP/IP Telnet stack.

Some VTAM applications allow only one simultaneous session per terminal or

ACB (logical terminal). This is called non-parallel session processing. Examples

include Customer Information Control System (CICS) and Information

Management System (IMS™). If a VTAM application can use the same ACB for

any number of sessions, this is called parallel session processing. Examples

include Time Sharing Option (TSO). While they are not in reality either, TCP/IP

sessions can be considered the equivalent of a parallel session; therefore,

TCP/IP sessions do not require a virtual terminal for connection.

For either VTAM session type, Session Manager requires specific types of VTAM

LU definitions be in place for successful connection to any VTAM application.

Consult IBM Session Manager Installation and Getting Started, GC34-6285, for

details on creating VTAM LU definitions for Session Manager. For non-parallel

sessions, there has to be a pool of VTAM LUs defined that will be used as virtual

terminals by Session Manager.

1.6.1 Parallel sessions

The default ACB used for parallel sessions is specified by the SESACB

parameter on the SYSTEM statement. You can provide a substitute for the

default specification by setting the ACB parameter on the common session

parameters for APPL, USER, TERMINAL, LU, or PROFILE statements. This

may be substituted with variables or characters from the luname or userid. The

special characters are a hash symbol (#) and percent sign (#). The special

characters act as “mask” characters within the specification of the ACB name.

Use of the hash symbol will cause a character from the Session Manager LU

name variable to be placed at the same relative location in the new ABC name.

Use of the percent sign will have the same result, but the source of the character

is the Session Manager userid variable. For example, if the LU name is

L010ABCD and the overriding ACB specification is ####K1, the ACB name that

will be used is L010K1.

Note: When you chose the names to use for Session Manager virtual

terminals, be aware of the AUTOINSTALL rules in place for all CICS regions

that will have a connection with Session Manager.