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Load Structure

CA Gen software does not require you to understand load module structure to generate and install application systems. However, an understanding of the structure of load modules is an important aid to performance tuning and in the investigation of runtime error messages.

The road to creating a load module that is ready for execution in a specific environment can be described as having four stages:

  1. Creating Procedure Steps and Action Blocks using the Action Diagramming Tool.
  2. Creating Load Module Packaging definitions using the Packaging Tool.
  3. Creating Load Module source code using the Generation Tool.
  4. Creating Load Module object code using either the Generation Tool or one of the Remote Implementation Toolsets.

In the first stage, you implement the business rules of your organization with action statements.

In the second stage, you build a list that defines how you group procedure steps and action blocks into programs. This is influenced by the characteristics of the target operating system. Some systems are more effective with fewer but larger load modules while other environments are more effective with more but smaller load modules.

In the third stage, source code is generated which integrates:

In the fourth stage, monitor-specific constructs are included within the load module when it is installed. In the MVS environment, CA Gen supplied user exits in object form are link-edited into DLLS that are invoked during execution. In other environments, these user exits are linked to the load module during execution.

An analogy can be made between the top-down approach to programming and the usage of procedure steps and action blocks. In a top-down structured program, all code is contained within paragraphs. Control does not simply flow from the top of the program to the bottom, and there are no explicit GO TO commands. One main paragraph placed at the beginning of the procedural section controls the flow within the program by calling paragraphs. Each paragraph returns to the main paragraph upon completion. A CA Gen procedure step performs the function of the main control paragraph by issuing USE statements that invoke specific action blocks.

The term load module means the same thing in the IBM mainframe environment as it does to CA Gen. Other operating systems have their own terms for machine readable code that can be executed. Some of them include: