Some basic concepts and terminology

Sampling
The process by which Application Performance Analyzer measures activity – recording data observed during repeated, timed “snapshots”– is called “sampling.” Application Performance Analyzer saves the observed data in a “measurement file,” sometimes referred to as a “sample file.”
Non-intrusive technology
Application Performance Analyzer’s sampling mechanism is efficient, effective, and, above all, non-intrusive. Application Performance Analyzer’s measurement engine will never schedule any task to execute in the address space being measured.
The Application Performance Analyzer started task
This started task performs all of Application Performance Analyzer’s measurements. Normally, a single Application Performance Analyzer started task is active in a single MVS™ instance. In a multiple-MVS instance installation (including a sysplex), an Application Performance Analyzer started task needs to be active in each MVS instance in which measurements are to be performed.
The Application Performance Analyzer Listener started task
This started task manages the communication between the Application Performance Analyzer GUI and the Application Performance Analyzer started tasks. Multiple workstation GUI users communicate through one Listener to any compatible Application Performance Analyzer started task defined on a single MVS instance.
Multiple started tasks
In special situations you might want to run multiple Application Performance Analyzer started tasks in a single operating system instance. For example, you might want to do this when making a transition from one product version to the next. Each Application Performance Analyzer instance is identified by a unique four-character instance identifier. For simplicity, this manual discusses Application Performance Analyzer in the context of a single-instance configuration.
The Application Performance Analyzer product code and Application Performance Analyzer instance ID
The module name prefix (product code) used by Application Performance Analyzer is CAZ. We have chosen CAZ0 as the default Application Performance Analyzer instance identifier, and it is used for examples in this document.
The ISPF component
Application Performance Analyzer’s ISPF component provides the user with full, interactive access to the product’s functionality. A single, gateway dialog serves as the entry point to all interactive services. The interactive services fall into two basic categories: scheduling and managing measurement requests; and analyzing measurement data.
The Graphical User Interface
The Application Performance Analyzer graphical user interface (GUI) is a CICS Explorer plug-in that provides an alternative to the Application Performance Analyzer ISPF interface. It communicates with the Application Performance Analyzer started task through the Application Performance Analyzer Listener started task.
Common data store
An optional data set unique to each Application Performance Analyzer started task (except in a sysplex environment), used to store lists of data set and directory names containing source program mapping files, and source program mapping associations. It includes one common list of data set names that can be shared amongst all users, and personal source mapping file lists for individual users. Individual users maintain their personal source mapping file lists using the ISPF A03 and A04 panels or the GUI Mapping Repository feature. Administrators maintain the common source mapping file list using the ISPF A05 panel or the GUI Mapping Repository feature.
IEFUSI exit routine
One Application Performance Analyzer module will receive control during the initiation of all job steps and started tasks, via the Step Initiation Exit (IEFUSI). During execution of this exit routine, Application Performance Analyzer determines whether a measurement has been scheduled for the job step, or started task. If it has, the exit routine will initiate sampling for the target address space. Application Performance Analyzer requires that the exit module (CAZ00990) in library hlq.SCAZLINK be added to the LNKLST.
Post-process initiation exit
One Application Performance Analyzer module will receive control during the initiation of all USS processes via the Post-process initiation exit (BPX_POSPROC_INIT). During execution of this exit routine, Application Performance Analyzer determines whether the process is a child process of one that is currently being measured by Application Performance Analyzer. If it is, the exit routine will initiate sampling for this target process. Application Performance Analyzer requires that the exit module (CAZ00991) in library hlq.SCAZLINK be added to the LNKLST.
IEFU83 exit routine
This is an optional SMF Record exit that Application Performance Analyzer will enable when measuring WebSphere applications. The exit will receive control whenever the SMFWTM or SMFEWTM macro is invoked by WAS. It captures SMF type 120 subtype 9 records for active sampling requests that have the WAS data extractor turned on. All other SMF records are ignored. Application Performance Analyzer requires that the exit module (CAZ00993) in library hlq.SCAZLINK be added to the LNKLST. When this exit is enabled, you must determine the amount of above-the-bar common storage that a WAS sampling session is permitted to allocate. This value is specified in the MemObjSize in the Application Performance Analyzer-started task configuration.
IEFU84 exit routine
This is an optional SMF Record exit that Application Performance Analyzer will enable when the DB2 SMF configuration option has been enabled. The exit will receive control whenever the SMFWTM or SMFEWTM macro is invoked by DB2. It captures SMF type 101 records for active sampling requests that have the DB2+ data extractor turned on. All other SMF records are ignored. Application Performance Analyzer requires that the exit module (CAZ00993) in library hlq.SCAZLINK be added to the LNKLST. When this exit is enabled, you must determine the amount of above-the-bar common storage that a DB2+ sampling session are permitted to allocate. This value is specified in the MemObjSize in the Application Performance Analyzer-started task configuration.
J9VM sampling module
One Application Performance Analyzer module is dynamically loaded and invoked by the JVMTI agent module CAZJVMTI (for 31-bit) or CAZJ64TI (for 64-bit) when sampling Java V5 & V6 jobs. The module processes requests by CAZJVMTI (for 31-bit) or CAZJ64TI (for 64-bit) to record Java sample data in the sampling data space. Application Performance Analyzer requires that modules CAZ00102 (called by CAZJVMTI) and CAZ00104 (called by CAZJ64TI) in library hlq.SCAZLINK be added to the LNKLST.