The DEBUGGING MODE clause is written as part of the SOURCE-COMPUTER paragraph in the Environment Division. It serves as an object-time switch over debugging statements written in the program.
When the WITH DEBUGGING MODE clause is specified in a program, all debugging sections and all debugging lines are handled as specified in this section of the document.
When the DEBUGGING MODE clause is not specified in a program, all the debugging sections and debugging lines are treated as if they were comment lines and their syntax is not checked.