Breakpoints

Breakpoints are used to suspend program execution at specified locations so that you may execute various debugging actions, such as evaluating variables, single statement stepping, and so on. The Breakpoint facility is used to set a breakpoint at a specified statement or to modify the characteristics of a breakpoint already set at that statement. Up to 64 breakpoints can be active at any one time. Breakpoints may be conditional and may have associated action lists (sequences of debugger commands to be executed when the breakpoint is incurred).

There are three pertinent commands to the Breakpoint facility: BREAKPOINT, NBREAKPOINT, and LBREAKPOINT:

• The BREAKPOINT command is used for adding new breakpoints and modifying existing breakpoints.
• The NBREAKPOINT command removes either a specified breakpoint or all breakpoints.
• The LBREAKPOINT command lists information about breakpoints.