You need to pass the dictionary object, not the dictionary name. So you would pass in a parameter of "serviceForm.DictName", which is the dictionary object. Then, if your parameter name was "objDict", you would call methods against it, for example: "objDict.setVisible(false);" and "objDict.FieldName.getValue();"
If, for some reason, you do need or want to pass a string of the dictionary name, you need to use the "eval" method to get the dictionary object back: eval("serviceForm." + dictString + ".FieldName.getValue()");