Easier for you doesn't mean more efficient. Not using dynamic array means that you must have a limited amount of space where you can store the lines. With dynamic arrays this space is, well, dynamic and you don't need to worry about anything failing.
It's really not complicated at all. You can use the code as is, but I suggest you use the array with a global variable.
PHP Code:
// this creates the array
// it's the same as "new StoreData[128][128]" you used, only here you're not limited to 128 lines
// you should define a global variable and then use ArrayCreate() inside plugin_init() or before reading the file
new Array:myArray = ArrayCreate(128)
// this adds the string (the entire line) in the array
// same as using "StoreData[line++] = data"
ArrayPushString(myArray, szData)
// this gets the number of elements (strings) stored in the array
// same as using "sizeof(StoredData[])", although this one should be cached
ArraySize(myArray)
// this is a neat "trick" for retrieving a string from a dynamic array
// same as using %s + StoredData[i]
ArrayGetStringHandle(myArray, index)
// the only difference is that you must destroy the array when you're done using it
// if you assigned it as a global variable, it's best to destroy it in plugin_end()
ArrayDestroy(myArray)
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