Thread control block

Thread Control Block (TCB) is a data structure in an operating system kernel that contains thread-specific information needed to manage the thread.^[1] The TCB is "the manifestation of a thread in an operating system."

Each thread has a thread control block. An operating system keeps track of the thread control blocks in kernel memory.^[2]

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: Points to the current program instruction of the thread
• 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.

See also

• Parallel Thread Execution
• Process control block (PCB)
• Thread Environment Block (TEB)

References

1. "Thread Control Block in Operating System". GeeksforGeeks. 2019-11-26. Retrieved 2023-09-04.
2. "CS162 - Fall 2014 #7 - Kernel Threads". inst.eecs.berkeley.edu. Archived from the original on 2023-12-07. Retrieved 2023-12-07.