Thread Control Block (TCB) is a data structure in the operating system kernel which contains thread-specific information needed to manage it. The TCB is “the manifestation of a thread in an operating system”.
An example of information contained within a TCB is:
- Thread Identifier:Unique id (tid) is assigned to every new thread
- Stack pointer: Points to thread’s stack in the process
- Program counter
- State of the thread (running, ready, waiting, start, done)
- Thread’s register values
- Pointer to the Process control block (PCB) of the process that the thread lives on
The Thread Control Block acts as a library of information about the threads in a system. Specific information is stored in the thread control block highlighting important information about each process.