SIZE_Ax
#define GETARG_Ax(i) getarg(i, POS_Ax, SIZE_Ax)
#define SETARG_Ax(i,v) setarg(i, v, POS_Ax, SIZE_Ax)
#if SIZE_Ax < LUAI_BITSINT-1
#define MAXARG_Ax ((1<<SIZE_Ax)-1)