I'm developing a Windows 8.1 App with Html/JavaScript. The app is for my company and I can't say what it does, but the app is bussiness critical. In some scenario our machines can reach 90% of RAM usage and the App is terminated by the OS. I've watched that other Apps are terminated as well, except Microsoft Apps like Skype, Lync etc, they don't get terminated. My question is how can I make my app so that the OS can't terminate it?
Those apps have background tasks that are run with a very low resource quota. Your app can have background tasks too, but you need to run within the constraints applied to those tasks. background tasks have no UI and can't depend on the UI parts of your app. See BackgroundTaskBuilder and related APIs.