Process Control Block

The Process Control Block (PCB) is a fundamental kernel data structure that represents a process in an operating system. It contains all the essential information needed to manage and track a process throughout its lifecycle. The PCB typically includes process identification data (process ID, parent process ID, user ID), processor state information (register values, program counter, stack pointer), process control information (scheduling state, priority, scheduling parameters), memory management information (page tables, memory limits, segment information), accounting information (CPU time used, time limits, account numbers), and I/O status information (list of open files, I/O devices allocated). When a process is created, the OS allocates a PCB and initializes it with the appropriate values. During context switching, the current process's state is saved in its PCB before loading the state of the next process to run. The PCB enables the OS to suspend and resume processes, manage process hierarchies, and maintain isolation between processes. Understanding the PCB structure is crucial for system programmers and OS developers as it represents the complete execution context of a process and is central to process management operations.