Search returned this question: Is there a limit to the length of a GET request?
To conclude: in specifications no limit is set for GET request size, but some web browsers set limits (for example, IE, which limits the GET request size to about 2000 characters). Also, from my own experience I know that some web servers (like Apache) allow to configure the maximum GET/POST request size, but this depends on which web server You are using in the backend.
Suggestion: use POST instead of GET, if You need to have bigger request size than 2000 characters. Verify whether Your web-server sets limits to GET/POST request sizes or not.