In modern operating systems, understanding memory management between processes and threads is critical for software development. A process represents an isolated running program, while threads function as execution paths within that process. The key architectural requirement is that each thread must maintain its own separate stack, even as threads share code, data, and heap memory within the same process.

This separation is essential because if threads attempted to share a single stack, their function calls would collide, corrupting local variables and causing program failure. The OS kernel orchestrates this through Thread Control Blocks (TCBs), which track each thread's unique stack pointer and execution state. When a function is called, a stack frame is pushed onto the thread's specific stack, adhering to LIFO (Last In, First Out) principles.

This design allows concurrent execution without interference. For example, in a music player, the UI thread can handle user input while a background thread decodes audio, both operating independently on their own stacks. This fundamental OS architecture ensures data integrity and enables the multitasking capabilities developers rely on.