I know that the TSTP will stop the process that were executing, and the signal id is 20, and it's equal to ctrl+z.
I searched for the abbreviation, but i didn't find anything! anybody know?
Literally "temporary stop".
You can find it mentioned in old(er) papers such as Evolving the UNIX System Interface to Support Multithreading Programs (Paul R. McJones and Garret F. Swart, September 28, 1987):
If a signal is received for which no handler procedure was registered, a default action takes place. Depending on the signal, the default action is either to do nothing, to terminate the process, to stop the process temporarily, or to continue the stopped process.
To stop a process, send it a stop signal (e.g., SigTStp; see page 44). To restart a stopped process, send it a continue signal (SigCont).
By the way, 4.3BSD's
<signal.h> has a different slant:
#define SIGTSTP 18 /* stop signal from tty */
Terminal SToP. It's a catchable signal, usually generated from the terminal with Ctrl Z.
Contrast with STOP, which has the same effect but cannot be caught.
See POSIX signal.h