Just My Code is a Visual Studio debugging feature that automatically steps over calls to system, framework, and other non-user code.
Tools-->Options-->Debugging-->General-->Enable Just My Code
Enable Just My Code is a global setting that applies to all Visual Studio projects in all languages.
In .NET projects, Just My Code uses symbol (.pdb) files and program optimizations to classify user and non-user code. The .NET debugger considers optimized binaries and non-loaded .pdb files to be non-user code.