I think the easiest way to do this is to create a dictionary that stores each stock's entry. For example, you can access a certain stock's entry by doing:

context.entries[stock]  

I made an example below. I also have to check that we have previously calculated an entry for a certain stock, which is why I added the first part to the if statement.

Hopefully that helps!

Or you could use the zipline SIDData object as a dynamic property base. You can effectively stick any named property to a SIDData object and it will hang around as long as you need it. This backtest does a gap open test instead of your other given test.

The strategy keeps the SIDData objects in a context.S collection. And then you can just stick stuff to them:

context.S[stock].MyFavoriteFood = "Twinkies"  
context.S[stock].ConsumedPerYear = 18234  

Also notice the history() call is outside of the 'for' loop since history already has the history for every stock in data (so no need to re-run history() inside the loop each time).
Another point generally (although it might not apply so directly to the code above): At one time I recall running into a cryptic message doing for stock in context.stocks that took a skype session with Q to figure it out, it was merely because a stock had no trades during that bar, and I was bitten by it way down the line in another function, so ever since then I stick with for stock in data, or for some other purposes for stock in context.portfolio.positions, just never for stock in context.stocks, recommend shying away from that. You can see MT has some safeguards.
Notice the vertical alignment of equal signs in Market Tech code, makes for easier reading.
You can even run wild with white space like I do:

        c.highs  = history(period, '1d', 'high') .bfill().fillna(1)  
        c.lows   = history(period, '1d', 'low')  .bfill().fillna(1)  
        c.prices = history(period, '1d', 'price').bfill().fillna(1)  

...or:

        if show_beta:       do_show_beta(      c, sec)  
        if show_volatility: do_show_volatility(c, sec)  
        if show_drawdown:   do_show_drawdown(  c, sec, price)  

(c = context) There's virtually no performance hit, Python runs a built version that removes all white space, and comments.
Part of the reason I posted that is that I'm not sure of what I'm doing with the fills in case anyone has a definitive tip.