If an error condition occurs, this routine returns an integer
    value indicating the type of error. Possible return values are as
    follows:

    Return      Description

    0           Successful completion.
    [EINVAL]    The value specified by attr is not a valid thread
                attributes object, or the value specified by
                stacksize either is less than PTHREAD_STACK_MIN or
                exceeds a Threads Library-imposed limit.