CORESIZE
#define MAX_MALLOC (size_t)(SIZE_MAX - CORESIZE - 3 * ALIGN) /* overflow chk */
n = ((n - 1) / CORESIZE + 1) * CORESIZE;
#define MAX_MALLOC (size_t)(SIZE_MAX - CORESIZE - 3 * ALIGN) /* overflow chk */
n = ((n - 1) / CORESIZE + 1) * CORESIZE;