z/OS fallback, coexistence, and migration options

When planning your next release migration, you need to consider which releases you can migrate to in a single step and what the fallback options are. In addition, if you have more than one z/OS image, you may need to consider the coexistence options for different releases.

The table below explains these options for the currently supported releases of z/OS.

Using the table below, find the release that you are currently executing in Column A. Column C, labeled Looking forward lists the releases that can be migrated to in one step. Column B, labeled Looking backward, lists the releases that you can fallback to. As for sharing resources between releases:
 

  • If the release in Column A is the highest executing release: Column B, labeled Looking backward, lists the releases that can coexist with the release in Column A.

  • If the release in Column A is the lowest executing release: Column C, labeled Looking forward, lists the releases that can coexist with the release in Column A.


COLUMN A COLUMN B COLUMN C
Release Looking backward (i.e. The release in column A is the highest executing release), the release in column A may coexist with or fallback to: Looking forward (i.e. The release in column A is the lowest executing release), the release in column A may coexist with or migrate in one step to:
OS/390 2.10
(EOS - 9/04)
OS/390 2.9
OS/390 2.10
OS/390 2.10
z/OS 1.1
z/OS 1.2
z/OS 1.3
z/OS 1.4
z/OS 1.1
(EOS - 3/04)
OS/390 2.9
OS/390 2.10
z/OS 1.1
z/OS 1.1
z/OS 1.2
z/OS 1.3
z/OS 1.4
z/OS 1.2
(EOS - 10/04)
OS/390 2.9
OS/390 2.10
z/OS 1.1
z/OS 1.2
z/OS 1.2
z/OS 1.3
z/OS 1.4
z/OS 1.5
z/OS 1.3
(EOS - 3/05)
OS/390 2.9
OS/390 2.10
z/OS 1.1
z/OS 1.2
z/OS 1.3
z/OS 1.3
z/OS 1.4
z/OS 1.5
z/OS 1.6
z/OS 1.4
(EOS - 3/07)
OS/390 2.10
z/OS 1.1
z/OS 1.2
z/OS 1.3
z/OS 1.4
z/OS 1.4
z/OS 1.5
z/OS 1.6
z/OS 1.7
z/OS 1.5
(EOS - 3/07)
z/OS 1.2
z/OS 1.3
z/OS 1.4
z/OS 1.5
z/OS 1.5
z/OS 1.6
z/OS 1.7
z/OS 1.8
z/OS 1.6
(EOS - 9/07)
z/OS 1.3
z/OS 1.4
z/OS 1.5
z/OS 1.6
z/OS 1.6
z/OS 1.7
z/OS 1.8
z/OS 1.7
(EOS - 9/08**)
z/OS 1.4
z/OS 1.5
z/OS 1.6
z/OS 1.7
z/OS 1.7
z/OS 1.8
z/OS 1.9
z/OS 1.8
(EOS - 9/09)
z/OS 1.5
z/OS 1.6
z/OS 1.7
z/OS 1.8
z/OS 1.8
z/OS 1.9
z/OS 1.10
z/OS 1.9
(EOS - 9/10)
z/OS 1.7
z/OS 1.8
z/OS 1.9
z/OS 1.9
z/OS 1.10
z/OS 1.11
z/OS 1.10
(EOS - 9/11**)
z/OS 1.8
z/OS 1.9
z/OS 1.10
z/OS 1.10
z/OS 1.11
z/OS 1.12


Legend


* Projected information — either projected dates or projected releases of z/OS — and represent current IBM intentions. Release numbering of future releases (later than z/OSV2R1) is for illustrative purposes and is not a guarantee of actual release numbers.


** IBM Lifecycle Extension for z/OS is an optional priced service.


The IBM Lifecycle Extension for z/OS V1.10 (5656-A01) provides fee-based corrective service (a fix, bypass, or restriction to a problem) for up to two years beyond the September 30th 2011 withdrawal of service date for z/OS V1.10.


The IBM Lifecycle Extension for z/OS V1.11 (5657-A01) provides fee-based corrective service (a fix, bypass, or restriction to a problem) for up to two years beyond the September 30th 2012 withdrawal of service date for z/OS V1.11.


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