Output component selection

IMS system definition allows a workstation to have a maximum of four output components.

If more than four output components are required for a workstation, or multiple LTERMs are not desired, a user-defined MPP-to-workstation protocol and data format must be provided.

Workstation components are assigned an identification number: X'01', X'02', X'03', and X'04'. For Finance terminals, the identification number is based on the order in which they are defined. For SLU P terminals, the identification number defaults to Comp¹, (Program1, Basic). IMS nonqueued system messages have no specific destination and are directed to the first component.

An IMS Transaction Input edit routine can be used to append the station's node name to the input message. The MPP can reference the node name to determine which LTERM name to use for output. For terminals created using the Extended Terminal Option (ETO) feature, append the user name to the input message because the user could be signed off.

To return a reply message to a workstation operating in terminal response mode, or to a conversational transaction, the MPP must insert the reply to the I/O PCB. However, for some stations, that reply message might be intended for a component other than the one associated with the LTERM specified in the I/O PCB. Because the destination of the I/O PCB cannot be modified by the CHNG call, an alternate PCB type is required. The alternate PCB type must fulfill these response requirements and also be modifiable. The PCB type, called the response alternate PCB, can be defined using PSBGEN. This PCB can be used instead of the I/O PCB to return reply messages to conversational transactions and to stations operating in terminal response mode. It can also be defined as modifiable. This allows the CHNG call to be used with this PCB to select the appropriate destination for the reply. When the CHNG call is used, the LTERM specified in the call must be assigned to the same physical terminal as the LTERM specified in the I/O PCB. If this is not the case, a status code is returned on the ISRT call.