HTTP 414 On Post Request- Me or My Shared Host?

Question

I am sending a post request using Angular $http with a request URI between 10,000 and 11,000 characters to an Apache (shared-hosting) server.

The server rejects my connection attempt, saying HTTP 414 Request-URI Too Large

My question is, why is this happening at a POST request?

According to these two posts:

1. maximum length of HTTP GET request?

2. What is the size limit of a post request?

The 8192 limit the server is telling me about should only apply to GET requests, unless I am misunderstanding something?

So am I doing something wrong or is the shared host misconfigured?

Because it is shared hosting, I don't have access to Apache configuration files.

Assuming I can't get around a weird POST limit on the server, how can I send this large request to a PHP script? Do I have to take advantage of SESSION to store, for example, the order JSON on a first $http and then combine this SESSION data with the rest of a second $http to get the complete order?

Does that make sense?

My POST request:

$http({
        method: 'POST',
        url: 'https://www.example.com/placeanorder',
        params: {
            order: angular.toJson($scope.order),
            orderProperties: angular.toJson($scope.Oproperties),
            token: token,
            totalCost: $scope.totalPrice,
            shippingCost: $scope.shippingCost,
            shippingProperties: angular.toJson($scope.shippingProperties)               
        }
    })