For reference purposes, here are the sizing limitations of the formula language:
The maximum length of a String constant, a String value held by a String variable, a String value returned by a function or a String element of a String array is 65,534 characters.
The maximum size of an array is 1000 elements.
The maximum number of arguments to a function is 1000. (This applies to functions that can have an indefinite number of arguments such as Choose).
There is no limit on the size of a function.