GLOBAL MARKETS-Shares tick lower ahead of earnings, euro steady

* US stocks down ahead of earnings, profits seen limp * Euro zone data points to stabilization of weak economy * Dollar falls vs yen after sharp, rapid rise * Oil edges higher; copper ticks lower By Ryan Vlastelica NEW YORK, Jan 8 (Reuters) - Global shares fell on Tuesday, with U.S. investors cautious ahead of an earnings season expected to show sluggish growth in corporate profits. European shares were flat as data showed the euro zone economy may be stabilizing, thoug