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WebSphere for z/OS V6.1 - 64-bit Addressing Support

Document Author:
Additional Author(s):

Don Bagwell
Nick Carlin

Document ID:


Doc. Organization:

Advanced Technical Sales

Document Revised:


Product(s) covered:


Abstract: WebSphere Application Server for z/OS Version 6.1 now has the ability to support starting servers in 64-bit addressing mode. That support was provided with V6.1.0.4, recently made available. This white paper provides information on what 64-bit address mode is, what it provides, and how it is enabled and used in a WebSphere for z/OS configuration. The default operating mode remains 31-bit, but it is now possible to tell WebSphere to allow a server to be started with AMODE=64. The JVM heap sizes may then be defined well in excess of the previous limit, which was 2GB. With 64-bit a JVM heap can be set to 16 exabytes, which is a whole lot of heap.

The paper is approximately 45 pages long.

In addition, a Powerpoint presentation is included that tells the same story as the white paper, but with pictures and a little less detail. The Powerpoint presentation has "speaker notes" under each picture with a narrative of the chart. The speaker notes provide sufficient detail, but not as much as the white paper provides.

WP100920 - 64 Bit Addressing Support.pdf WP100920 - 64-bit Addressing Powerpoint.ppt




Planning and Design


IBM System z Family

S/W Pillar(s):





WebSphere z/OS, 64-bit, JVM

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