Using Breakpoints

A breakpoint indicates a line of code or program at which you want the execution of an application to pause. When the application is paused, you can view and change the values of data items at that particular step. The Breakpoints Properties view shows details of all bound breakpoints and enables you to configure them.

When using the Visual Studio Debugger to debug PL/I code, Enterprise Developer provides five types of breakpoints you can set. They are:

Standard breakpoints

These are set on a selected line of code within a PL/I program, and cause the debugger to stop before executing that line of code. These work in PL/I code the same as in COBOL native code.

Program breakpoints

This type of breakpoint breaks debugger execution before executing a specific called program.

Note: This type of breakpoint only breaks execution the first time the debugger encounters the specified called program. On subsequent encounters, the debugger does not break.

Condition breakpoint

A condition breakpoint instructs the debugger to notify you when a defined condition is met.

Signal breakpoint

A signal breakpoint instructs the debugger to notify you when a specific signal is encountered.

Data breakpoint

A data breakpoint breaks execution when a specified memory location is written. Use of data breakpoints assumes expert-level knowledge of how memory works, how variables are allocated, and how data is written to memory.

Two-byte ranges must be aligned on word boundaries; 4-byte ranges must be aligned on double-word boundaries.

When monitoring user-allocated memory, we recommend that you remove data breakpoints before the memory is freed, otherwise the behavior is undefined.

Restriction: You may set up to four data breakpoints per debug session. Each breakpoint can monitor 1, 2, 4, or 8 bytes of memory.

In addition, you can also set watchpoints. A watchpoint is a type of breakpoint that helps you track memory corruption in PL/I code; however, rather than setting watchpoints on specific lines of code, you set them on individual data items. A watchpoint enables you to watch an area of memory associated with the particular data item. When the memory is updated or a user-defined condition is satisfied (for example, memory updated a specific number of times), debugging stops on the line that immediately follows the line that changes the data.