Final answer:
In a multithreaded system, the runtime stack is associated with each individual Thread, with each one maintaining its own function calls and execution state independently of others.
Step-by-step explanation:
In a multithreaded system, the runtime stack is associated with each individual Thread. This is because each thread needs to keep track of its own function calls, local variables, and return addresses, which are all stored in the runtime stack. The runtime stack is crucial for a thread to maintain its own execution state independently of other threads. Therefore, even if there are threads in a process, each one will have its own runtime stack. With a separate runtime stack, threads can be preempted, or interrupted, allowing the operating system to switch between threads seamlessly, which is key to the efficient execution of a multithreaded process and helps optimize the use of available CPU time.