IBM z/OS - Manual (Page 77)

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This consistent coexistence, migration and fallback policy
applies to release migrations for:
• Single system confi gurations
• Individual systems within a multisystem confi guration
• Cases where a simultaneous IPL is used to migrate all
systems in a multisystem confi guration at the same time.
For additional information on coexistence and release
migration information, refer to z/OS Planning for Installation
(GA22-7504) at: ibm.com/servers/eserver/zseries/zos/
bkserv/fi nd_books.html.
The following table describes the migration/coexistence
supported releases. The release shown in column 1 is the
highest release running in a multisystem confi guration.
Migration/Coexistence Supported Releases (OS/390 & z/OS)
Release Migration/Coexistence Release
z/OS R4 z/OS R4, z/OS R3, z/OS R2, {z/OS R1, OS/390 R10}
z/OS R5 z/OS R5, z/OS R4, z/OS R3, z/OS R2
z/OS R6 z/OS R6, z/OS R5, z/OS R4, z/OS R3
z/OS R7 2 z/OS R7, z/OS R6, z/OS R5, z/OS R4
1. OS/390 R10 and z/OS R1 treated as one coexistence level
2. z/OS R7 is planned to be available September 2005
This information is being provided to you to facilitate
release planning and to help ensure appropriate position-
ing for future software migrations.
Note: Specifi c functions might only be available on the
up-level systems, or it might be necessary to up-level all
systems to enable some functions.
For additional information on z/OS planning, refer to z/OS
and z/OS.e Planning for Installation, available on the z/OS
Web site in the z/OS Library at: ibm.com/servers/eserver/
zseries/zos.
For the latest information regarding z/OS and OS/390
marketing and service withdrawal dates visit: ibm.com/
servers/eserver/zseries/zos/support/zos_eos_dates.html.
Migration, installation and customization
enhancements
For information on migration to the latest z/OS releases,
see the z/OS Migration Web page ibm.com/zseries/zos/
migration. The publications are available from this site for
helping to plan the migration to z/OS 1.6.
zSeries Bimodal Support for z/OS
IBM provides is announcing the z/OS Bimodal Migration
Accommodation Offering to assist customers in migrat-
ing from OS/390 to z/OS. This addresses many customer
requests to have a “fallback” option to 31-bit mode when
fi rst migrating to z/OS in 64-bit mode on a z/Architecture
server. IBM has reconsidered the investment in 31-bit sup-
port on a zSeries server to encourage our customers to
move forward. This offering is available for 6 months for
each z/OS license (5694-A01) starting from the registration
of a z/OS license to a z/Architecture server. This offering
applies to z/OS Version 1 Release 2, 3, and 4, and will not
be provided for z/OS 1.5 or for any z/OS.e releases.