I have faced such issues in the past.
On your receiving end you normally encounter a 414 Request-URI Too Long-header.
We cannot increase it at runtime. In Apache webserver if you are using it as a webserver then you can limit it to up to 8190 bytes, but not above it without changing your source code & recompiling.
It is completely server dependent and also the UA-dependent, and if you are running Suhusoin with PHP then more possible rules will apply to you.
Such problem arises if your form method is not set and if it tries to fetch the variables from a session. To fix this you need to set the form method as method="POST" then it will surely work.
You can also store your data on a database. After that you need to assign the unique ID to your data
You can pass your ID in your URL. Then you can retrieve the data from database using a ID as key