John Q

All of an application's default stack space is allocated to the first thread of execution, which is known as thread 1. As a result, you must specify how much memory to allocate for a separate stack for each additional thread your program needs. The operating system allocates additional stack space for the thread, if necessary, but you must specify a default value.
The first argument in the _beginthread call is a pointer to the BounceProc function, which executes the threads. The second argument specifies the default stack size for the thread. The last argument is an ID number that is passed to BounceProc. BounceProc uses the ID number to seed the random number generator and to select the thread's color attribute and display character.
Threads that make calls to the C run-time library or to the Win32 API must allow sufficient stack space for the library and API functions they call. The C printf function requires more than 500 bytes of stack space, and you should have 2K of stack space available when calling Win32 API routines.
Because each thread has its own stack, you can avoid potential collisions over data items by using as little static data as possible. Design your program to use automatic stack variables for all data that can be private to a thread. The only global variables in the Bounce.c program are either mutexes or variables that never change after they are initialized.