XML error parsing SOAP payload on line 1: No memory using nusoap_client in laravel

I want to retrieve huge records data from an external API. But when I execute function to do this, i get an error like this :

XML error parsing SOAP payload on line 1: No memory

This is My function code:

public function get_all_data(){
     ini_set("max_execution_time", "-1");
     ini_set("memory_limit", "-1");
     ignore_user_abort(true);
     set_time_limit(0);

     $url = "http://xxx.xx.x.xx:xxxx/services/DS_Get_Pending?wsdl";
     $client = new \nusoap_client($url, 'wsdl');

     $pDate = isset($_GET["pDate"]) ? $_GET["pDate"] : '26/02/2017 01:01:01';
     $operation = 'getPending';
     $param1 = array(
         'pDate' => $pDate,
     );
     $result = $client->call($operation, $param1);
     print_r($result);
     exit();
}

How to fix this error?

via Chebli Mohamed