TIL, the German #Datev uses #IBM #zOS for paycheck #PDF generation. PDFs are generated through PDFlib by the Munich based company of the same name:

PDF producer: PDFlib+PDI 9.0.4-m (zSeries z/OS)

The API ref is promising some fun:
"For use with C, C++, Cobol, COM, Java, .NET, Objective-C, Perl, PHP, Python, REALbasic/Xojo, RPG, Ruby"
(https://www.pdflib.com/fileadmin/pdflib/pdf/manuals/PDFlib-9.0.4-API-reference.pdf)

As well as:
"PDFlib is available on a variety of platforms, including Unix,
Windows, OS X, and EBCDIC-based systems such as IBM i5/iSeries and zSeries."
(https://www.pdflib.com/fileadmin/pdflib/pdf/manuals/PDFlib-9.0.4-tutorial.pdf)

And since IBM #zSeries does everything in #EBCDIC, this, of course is also supported:

"stringformat ebcdicutf8: All strings and option lists are expected in EBCDIC-UTF-8 format with or without BOM."

And although I do hope that Datev uses Unix System Services #USS instead of plain #MVS on z/OS, this does give me the creeps:

"MVS versions of PDFlib GmbH products are not thread-safe"
(https://www.pdflib.com/fileadmin/pdflib/System_Requirements/PDFlib-9.0.4-system-requirements.txt)

Truly curséd. But PDFlib on zSeries doesn't support networking ... unfortunately?