Process Control Block

operating-systems

Definition

Process Control Block

The Process Control Block (PCB) is a data structure representing the execution context of a specific process. It serves as the repository for any information that may vary from process to process.

Components

The PCB typically contains:

• Process Identification: Unique identifiers (PID, Parent PID, User ID).
• Processor State: The context required to resume execution (program counter, stack pointer, PSW, general registers).
• Memory Management: Pointers to page tables or segment tables.
• Control Information: Scheduling state (ready, blocked), priority, I/O status, and open file descriptors.

Location

Kernel Residence

The PCB resides in kernel space and is a component of the process image. The set of all PCBs is indexed by the primary process table.