Now that the holiday shopping season behind us, Zara is preparing to start construction on its new space at Westfield Montgomery mall — and it’s a whole lot bigger than expected. The two-level store — carrying men’s, women’s and kids’ clothing — will take over a substantial portion of the Nordstrom wing, across the hall from Zara’s current location. On the upper level, Zara will occupy the entire space between Tumi and Johnston & Murphy. On the lower level, it will run from Warby Parker to Beauty Frizz — possibly including the just-closed Socks Be To You space. If all goes according to plan, doors will open this fall.