Garbage collection is traditionally not used in real-time systems due to the unpredictable temporal behavior of current implementations of a garbage collector. However, without garbage collection the programming model is very different from standard Java. It is the opinion of the authors that garbage collection algorithms can be adapted to meet even the requirements for hard real-time systems.One important property of a real-time garbage collector is to identify only the real roots on the root scan. Misinterpreting primitive values as false root pointers can result in an unpredictable worst case memory consumption. In this paper we propose a method to add information on the stack layout to the runtime data structure in order to find the roots exactly. Furthermore, interpreting this information during the collection process is implemented to be worst-case execution time analyzable.