Portal | Manuals | References | Downloads | Info | Programs | JCLs | Mainframe wiki | Quick Ref
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Profile Log in to check your private messages Log in
 
What are the benefits and applications of IBM 64-bit?

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> PL/I & Assembler
View previous topic :: :: View next topic  
Author Message
Mistermind
Warnings : 2

New User


Joined: 08 Feb 2008
Posts: 46
Location: Dublin

PostPosted: Thu Apr 30, 2009 12:06 am    Post subject: What are the benefits and applications of IBM 64-bit?
Reply with quote

I just read How to convert from 31 addressing mode to 64 addressing mode and had a question.

Umey,

What are the practical benefits and applications of IBM 64-bit? And how is it selling, and to what installations? How is the performance and runtime aspect?
Back to top
View user's profile Send private message

Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8165
Location: East Dubuque, Illinois, USA

PostPosted: Thu Apr 30, 2009 12:19 am    Post subject:
Reply with quote

The hardware is running 64-bit already. Many applications, however, cannot take advantage of it. For example, Enterprise COBOL 3.4 Programming Guide says
Quote:
Enterprise COBOL does not directly exploit the 64-bit virtual addressing capability of z/OS; however, COBOL applications running in 31-bit or 24-bit addressing mode are fully supported on 64-bit z/OS systems.
A quick search of the IBM web site indicates that 64-bit is mostly used for Java, Websphere, and DB2 -- at least in the first several screens of search results.
Back to top
View user's profile Send private message
kumar40322

New User


Joined: 25 Apr 2009
Posts: 15
Location: Hyderabad

PostPosted: Thu May 14, 2009 11:53 pm    Post subject: what is 64 mb line?
Reply with quote

Hi

At this point i want to clarify one douibt!!! what is amode and rmode? how they can help for any program?what is above 64mb line and under 64mb line?
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8165
Location: East Dubuque, Illinois, USA

PostPosted: Fri May 15, 2009 12:17 am    Post subject:
Reply with quote

amode is addressing mode -- which refers to how many bits of address the program can use

rmode is residence mode -- which refers to whether the program can physically be placed in memory above the 16 meg line or not.

Code running below the line (16,777,216) -- also known as 24-bit code -- cannot typically use memory above the line, which limits the program. The operating system loads into memory below the line and usually there's only about 10 MB (or less) of the 16 MB that can actually be used by a program. If the program needs a large table, that could run it out of storage. Programs running above the line have 31-bit addressing and effectively have just under 2 GB of memory they can use.

So far as I know, there is no 64 mb line of any sort on a z/OS system, so I do not know what you are referring to -- can you clarify?

Terminology note: 64-bit code on z/Architecture has a 2GB bar (not a line); this refers to the fact that IBM prohibits programs running 64-bit mode from using any memory between 2 GB and 4 GB. This prohibition has to do with the way the bits are mapped for memory addresses. The program can use lots of memory between 4 GB and the upper limit of the system.
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> PL/I & Assembler All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
No new posts Benefits of removing DISPLAY statements mkk157 COBOL Programming 17 Thu Aug 13, 2015 12:38 pm
No new posts Extraction of applications and jobs p... omprakash.mf IBM Tools 9 Fri Mar 28, 2014 10:05 am
No new posts Migration of Cobol applications from ... tusharguptait COBOL Programming 3 Thu Nov 17, 2011 11:52 am
No new posts Installed applications on Mainframe enrico-sorichetti All Other Mainframe Topics 8 Sat Jun 04, 2011 11:50 pm
No new posts Self service password reset applications tmisicko All Other Mainframe Topics 2 Wed May 18, 2011 1:11 am

Facebook
Back to Top
 
Job Vacancies | Forum Rules | Bookmarks | Subscriptions | FAQ | Polls | Contact Us