<P> 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 a particular process . The PCB is "the manifestation of a process in an operating system ." </P> <P> 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 we previously mentioned . </P> <P> 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: </P>

What is the purpose of the process control block
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