如何使用Flysystem包管理L5类存储中的大文件上传？

In my Laravel 5 set up, I included the Flysystem package, configured a disk in config/filesystems.php (ftp)

'ftp' => [
        'driver' => 'ftp',
        'host'      => env('FTP_HOST'),
                    'username'  => env('FTP_USER'),
                    'password'  => env('FTP_PASS'),
                    'passive' => TRUE,
    ],

Then I'm able to perform ftp upload and download with the following instructions:

Storage::disk('ftp')->put($filePath, $contents);
Storage::disk('ftp')->get($filePath);

Until here everything is fine. Problems start when I'm uploading big files. Above 200MB. PHP memory limit is reached and execution stops with fatal error. In fact when Storage->put is called my PC memory increases dramatically.

I've read somewhere that a solution might be to use Streams to perform read write from my "virtual" disk.

Actually I'm still missing how to implement it in order to optimize memory usage during these operations.