Linux on IBM Z (also known as zLinux, Linux/390, or Linux/390x) is the collective term for the Linux operating system, including Red Hat Enterprise Linux, SUSE, and Ubuntu, compiled specifically for IBM Mainframe servers (Z and LinuxONE). It enables high-security, scalable, and energy-efficient workload consolidation, often hosting thousands of containers or virtual machines on a single machine, resulting in 99.999% uptime.