Using IBM Application Development Tools for z/OS and OS/390

Chapter 5. Using Application Monitor 201

5.1.5 Other uses

These are some other uses for Application Monitor:

򐂰 To provide information to a software provider when you run into a performance problem

with their code

򐂰 To help system programmers determine what parts of a given application are causing a

system performance problem.

5.2 Some things to remember when using Application Monitor

Application Monitor is a sampling profiler. That is, it randomly samples where the program it is

monitoring is, at an interval. This means that the profile it gives is not “exact” (that is, found by

following the code exactly and seeing what is executed) but “averaged”. To get the most out

of a sampling profiler, a user should ensure that they are basing their analysis on a significant

number of samples. It is also best if the program one is profiling runs at least 1 minute in

length.

For the first sample run through, we just used the Application Monitor defaults. For the follow

on COBOL/PLI/CICS and DB2 examples, we will be setting the defaults on the defaults

panel.

In general, we recommend capturing the data live (option 1) or deferred, and using the

analyze history files option (option 5) when doing the actual analysis.

It is also to the analyzer’s advantage to capture as much relevant data as possible.

Application Monitor does not currently support Statement Analysis for statically linked

modules coded in different languages.

5.3 Basic functionality

For the user, the center of Application Monitor’s power is a simple ISPF user interface. The

Primary options panel contains seven options as shown in Figure 5-1. The benefits of some

of these options are discussed below.

Note: When using either of the sub-screens accessible from the Set Your Defaults option

on the main menu, exiting using F3 (End) will cause your changes to be thrown away. In

order to keep the changes you set, you must save them to your ISPF profile before exiting

(F3)

202 Using IBM Application Development Tools for z/OS and OS/390

Figure 5-1 The Application Monitor Primary Options Menu

The primary source of information for Application Monitor is the IBM Application Monitor for

z/OS V2R1 Users Guide, SC18-9084-00.

5.3.1 Analyzing an active job

This option lets you see all the active jobs on the system and then select one to monitor. We

feel it has some definite ease-of-use advantages over option 2 because:

򐂰 It does not require that you remember

exactly how to spell the job name or CICS region

name.

򐂰 It has filter fields at the top of the panel where you list active jobs, so you can narrow down

the list of jobs to only the types of jobs you are interested in.

򐂰 It allows you to see where your application sits, in relationship to other running tasks, in

terms of system usage. (This is especially useful if you are developing a long running job

or permanently running tasks.)

򐂰 Finally, as an additional benefit, if some job is using up all the CPU on the system, a quick

look at option 1 can help you figure out who to call.

In reality, option 1 and 2 are just two different ways to get to the same functionality. You can

choose which one you prefer and get the information you want.

Once you have selected your job to analyze, Application Monitor starts collecting samples

and quickly presents you with some reports to view. These reports allow you to do things like:

򐂰 Find the highest use module in your application.

򐂰 Find the hottest CSECT in your highest use module.

򐂰 Find the most executed instruction sequence (or COBOL/PLI source code line) in a given

CSECT.

򐂰 See what system modules you are using.