TP-COBOL-Debugger is a debugger that allows the animation of a cobol program with the several functions of step by step, breakpoint (conditional, global, at line) data analysis and control flow graph functions that allow the automatic generation of gif files with the structure of the program. TP-COBOL-Debuger is an opensource project and was written in entirely with COBOL language. The debugger uses a pre-processor which analyzes the program and generates and compiles a copy integrating it with the debugging modules. Using cobol to wrote the debugger allows, in principle, to make the debugging functionality a customizable function and therefore, once integrated into the program, independent of the fact that the compiler is available on the test machine. The debugger allows the debug session to be activated on all animated programs called by the main program.  

Here a good guide written by :  Eugenio Di Lorenzo

NEWS: you can use it inside the GuiCOBOL gui library