Process control block

Process Control Block (PCB, also called Task Controlling Block, Entry of the Process Table, Task Struct, or Switchframe) is a data structure in the operating system kernel containing the information needed to manage the scheduling of a particular process. The PCB is 'the manifestation of a process in an operating system.' Process Control Block (PCB, also called Task Controlling Block, Entry of the Process Table, Task Struct, or Switchframe) is a data structure in the operating system kernel containing the information needed to manage the scheduling of a particular process. The PCB is 'the manifestation of a process in an operating system.' The role of the PCBs is central in process management: they are accessed and/or modified by most OS utilities, including those involved with scheduling, memory and I/O resource access and performance monitoring. It can be said that the set of the PCBs defines the current state of the operating system. Data structuring for processes is often done in terms of PCBs. For example, pointers to other PCBs inside a PCB allow the creation of those queues of processes in various scheduling states ('ready', 'blocked', etc.) that was previously mentioned. In modern sophisticated multitasking systems, the PCB stores many different items of data, all needed for correct and efficient process management. Though the details of these structures are obviously system-dependent, we can identify some very common parts, and classify them in three main categories: