[Fixed]-Submitting all forms on a page with JavaScript using ajax at once to Django

Your collect function can be simplified and then you can post all the data as json either with serializeArray or serialize, for example:

var alldata = {};

$("form").each(function(i, form){
  var current_data = $(form).serializeArray();
  alldata[$(form).prop("id")]  = current_data;
});
alert(JSON.stringify(alldata));

$.ajax({
  //your parameters here: url, etc.
  url: 'save_stacks',
  type: 'post',
  dataType: 'json',
  data: alldata,
  success: function(response) {
    //handling code
  }
});

https://jsfiddle.net/1pLn4hw1/

You will likely have to adapt your handling code in the backend.