Terminals and MFS

Whether your program uses MFS depends on the types of terminals and secondary logical units (SLUs) your network uses. You can bypass MFS formatting of an output message for a 3270 device or for SLU Type 2 devices. When MFS is bypassed, you construct the entire 3270 data stream from within your program.

Restriction: MFS cannot be used with LU 6.2 devices (APPC).

Related reading: For more information on LU 6.2 and APPC, see IMS Version 15.2 Communications and Connections.

Using MFS involves high-level design decisions that are separate from the tasks of application design and application programming; many installations that use MFS have a specialist who designs MFS screens and message formats for all applications that use MFS.

MFS makes it possible for an MPP to communicate with different types of terminals without having to change the way it reads and builds messages. When the MPP receives a message from a terminal, the message's format in the MPP I/O area depends on the MFS options specified and not on what kind of terminal sent it. MFS shields the MPP from the physical device that is sending the message in the same way that a DB PCB shields the program from what the data in the database actually looks like and how it is stored.