Process control block

A process control block (PCB), also sometimes called a process descriptor, is a data structure used by a computer operating system to store all the information about a process.

When a process is created (initialized or installed), the operating system creates a corresponding process control block, which specifies and tracks the process state (i.e. new, ready, running, waiting or terminated). Since it is used to track process information, the PCB plays a key role in context switching.

An operating system kernel stores PCBs in a process table.

The current working directory of a process is one of the properties that the kernel stores in the process's PCB.