All of it, up to the actual amounts of your gains for the current year. You can then deduct $3000 against ordinary income (on line 13 of form 1040). It doesn't matter if the current year gains are long or short term, the loss carry over is applied to all gains.
So, for example, if you have $50,000 in gains this year, your schedule D and line 13 of form 1040 will show a net $3000 loss and $147,000 will carry forward to next year.
