olemus
IBM suurarvutite 64-bitine operatsioonisüsteem (algversioon 2001)
= a 64-bit operating system for IBM z/Architecture mainframes

ülevaateid
https://en.wikipedia.org/wiki/Z/OS

turvalisus
http://wwwlgis.informatik.uni-kl.de/cms/fileadmin/users/kschmidt/mainframe/lutzkuehner/Chapter11_Security_on_zOS_slides.pdf
https://www.psrinfo.com/5-things-you-should-know-about-mainframe-security/
https://www.helpnetsecurity.com/2021/07/27/ibm-z-os-v2-5/
https://cdn2.hubspot.net/hubfs/121847/docs/CorreLog-whitepaper-11-steps-mf-security-feb17-4web.pdf