Performance considerations

There are three components to the overall efficiency of the part of your application that the end user sees: processor path length, communications line utilization, and user time. Path length and line time used to be paramount, and much design and programming effort has been invested in minimizing them.

As online systems have evolved, however, the emphasis has shifted steadily to making things as easy, pleasant and quick for the user as possible, at the expense of the other factors if necessary. Also, as processors have become cheaper, designers have been willing to expend cycles to reduce programming and maintenance effort as well as to make the user interface better.

We have already given you references on elements of good design for the user interface, in Personal computers, and usually these should be your overriding considerations. In this section, we point out some ways that you can reduce path length and line time as well. You need to judge for yourself whether and to what extent the savings justify extra programming effort or a less general design.

Minimizing path length

Ordinarily, the number of instructions executed in a single CICS® command is large in comparison to the number of instructions in the application program that invoked it. Consequently, the path length for a given task ordinarily depends more on the number and type of CICS commands than on anything else, and commands are the most fertile area for tuning. Commands vary by type, of course, and path length for any given command may vary considerably with circumstances.

For BMS, some recommendations are:

Reducing message lengths

You can take advantage of 3270 hardware to reduce the length of both inbound and outbound messages. If the bandwidth in any link between the terminal and the processor is constrained, you get better response overall with shorter messages. However, the time for any given transmission depends on the behavior of other users of those links at the time, and so you may not see improvement directly. Here are some of the possibilities for reducing the length of a 3270 datastream:

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