Restrict Payment file to 5000 records..

Hi,

I have typical client requirement. What we are looking is, to create one payment document to

Vendor that should contain max 5000 invoices per payment document.

If the Line items igoes beyong more than 5000, it should create another document.

This payment file is currently being created by ABAP.

How can we restrict this to create 5000 items per document?

Regards