Chapter 6. Software support 135
Draft Document for Review April 7, 2004 6:15 pm 6947ch06.fm
z990 Compatibility for selected OS/390, and z/OS releases
OS/390 V2.10, z/OS V1.2, and z/OS V1.3 require the Web delivered Compatibility support to
run on a z990.
Compatibility support allows these releases to:
򐂰Define a z990 environment with HCD
򐂰Run on a z990 processor in a logical partition in LCSS-0, using an LPAR id equal to or less
than x’F’.
򐂰Coexist in a sysplex that contains a z990 processor
򐂰Coexist with z990 processors sharing disk devices outside of a sysplex.

Compatibility support requirements

Compatibility support is required under the following circumstances.
򐂰Compatibility support is required for all images running on a z990.
򐂰Compatibility support is required on any image that is used for defining the I/O
configuration for the z990.
򐂰Compatibility support is required on all images in a sysplex, whether running on a z990 or
not, if a Coupling Facility logical partition for that sysplex is running on a z990 and has an
LPAR identifier greater than 15 ( x’F’).
Compatibility support allows the supported operating systems to run in LCSS 0 on the z990
processor. It is not possible to run z/OS or OS/390 in LCSSs 1, 2, and 3, even with the
compatibility maintenance. This is supported on z/OS 1.4 with the exploitation support and
subsequent releases.
Compatibility support can run on any processor that is already supported by one of the listed
operating systems. For example, you can install Compatibility support on a z/OS V1.2 system
that is running on a IBM 9672 G5 processor.
Figure 6-1 shows a situation where the Compatibility support is not required for systems not
on the z990.
Attention: Compatibility nor Exploitation support is not available for z/ OS 1.1
Note: A Coupling Facility logical partition can reside in any Logical Channel Subsystem