Process control block :

The responsibility of a OS is to collect all information that a process needs about a particular process into a data structure called PCB or JCB. A process in an operating system is represented by a data structure known as a process control block (PCB) or process descriptor.  When a process is created, the OS create a corresponding PCB and when it terminates its PCB is destroyed. The PCB contains important information about the specific process including

• The current state of the process i.e., whether it is ready, running, waiting etc.
• Unique identification of the process in order to track "which is which" information.
• A pointer to parent process.
• Similarly, a pointer to child process (if it exists).
• The priority of process (a part of CPU scheduling information).
• Pointers to locate memory of processes.
• A register save area.
• The processor it is running on.  

                                    

                                                                                 .......to be continued                                 R.P