Generate 2D barcodes and and arrange on a grid for bulk printing
Just FWIW, Code-128 is NOT a 2D barcode, it is a "simple" 1D barcode. 
That said, there are Code-128 fonts around, which means you can use them in PDF form fields, which you can fill, maybe flatten the document, and send to the printer. No need to fiddle around with layout, after you created your base PDF.
To fill, you could use command line tools, such as FDFMerge by Appligent, where you can easily create data files from your database system, and merge that data with the base PDF.
What tools do I need to render 60,000+ unique Code-128 barcodes and arrange them in a grid in a PDF file for volume printing? Printing this many barcodes digitally seems like a challenge on its own, so there must be some lore from folks who have dealt with warehousing and bulk labelling.
Existing projects and commercial products focus barcode generation instead of layout and printing. I messed around with some Python that renders a PDF, but the tough part is dealing with various labelling templates and understanding that printers print better or worse barcodes depending on the rotation of the heads.
Should I even be using PDF for this? I have spent too much time already trying to line up the output of an HTML page for a crappy labelling template. I would appreciate a link to an open source library or even commercial tool for laying out barcodes at this scale.