When Xdebug is activated it will show a stack trace whenever PHP decides to show a notice, warning, error etc. The information that stack traces display, and the way how they are presented, can be configured to suit your needs.
If this setting is 1, then stacktraces will be shown by default on an error event. You can disable showing stacktraces from your code withxdebug_disable(). As this is one of the basic functions of Xdebug, it is advisable to leave this setting set to 1.