Step 3. Check Your Virtual Machine's Architecture

Your virtual machine's user directory entry specifies the architecture of your virtual machine after a virtual system reset occurs, such as after LOGON or after an IPL command: XA, ESA, XC, or Z.

To IPL any operating system in your virtual machine, your virtual machine must simulate the appropriate architecture.
  • ESA virtual machines process according to ESA/390 (31-bit) architecture. ESA virtual machines are also capable of processing according to z/Architecture® (64-bit) if switched into that mode by a guest operating system.
  • XA virtual machines are supported for compatibility and are functionally equivalent to ESA virtual machines. Some CMS applications may require CMS to be running in an XA virtual machine.
  • XC virtual machines process according to ESA/XC or z/XC architecture. Guest operating systems can switch an ESA/XC virtual machine to a z/XC virtual machine.
  • Z virtual machines start in and process entirely in z/Architecture.

So, for example, VSE/ESA can run in an ESA or XA virtual machine. z/VM can run in an XA, ESA, or Z virtual machine. If z/VM is run in an XA or ESA virtual machine, it switches into z/Architecture during IPL.

Note: 370 virtual machines are not supported. For information on executing System/370 applications, see the SET 370ACCOM command in the z/VM: CP Commands and Utilities Reference.
To determine the architecture of your virtual machine, enter: 
query set

Part of CP's response is MACHINE XA, MACHINE ESA, MACHINE XC, or MACHINE Z.