>>>one can add a commet to a zip file itself. I store information on it, so I need to read and write
>>
>>You can add comment in the ZIP :-)
>>Check the last link I sent to you.
>
>Thanks, I see

There seems to be some limitation on zLib based zippers about the size of a single file they can zip. In my case (i.e. on my OS, available memory etc) it was that no zip could be larger than about 19 megabytes. It would save at that length and be invalid. Test your own. In my case, while I need to zip single files one at a time, these files may be videos of unknown length, so a limitation like that makes it a no-go.

I ended up using api_apprun (late Ed Rauh's stuff still works after ten years) to run pkzip25, the last freebie DOS style zipper from Phil Katz. I'm using the latter for 13 years now and it still hasn't failed. DOS style means the command line is your interface... and you can do anything with it.