INI files are not dead yet :)
Now if you wanted to disable JIT optimization then place this into your application directory as a <appName>.ini file
[.NET Framework Debugging Control]
Why would you want to do this?
Mostly when debugging in release mode you might not the get the correct stack dump. Eg: JIT might inline method definitions and you could actualy not see the method in which the exception is being raised. So when your debugging in a production environment. try to disable JIT optimizations before geting the stack dump.