env

    The environment buffer, which must be an array of integers long
    enough to hold the register context of the calling function.
    The type jmp_buf is defined in the <setjmp.h> header file. The
    contents of the general-purpose registers, including the program
    counter (PC), are stored in the buffer.

 value

    Passed from longjmp to setjmp, and then becomes the subsequent
    return value of the setjmp call. If value is passed as 0, it is
    converted to 1.