The 64-bit version of the Java SDKs use 64-bit LE Heap storage for the "Java heap" (which includes not only Java objects, but loaded class files).
I'm not certain about JITed methods (executable instructions), but I would assume that they are below the bar, in the "31-bit LE Heap". This could be confirmed in a dump that included JIT'ed code. The best information is probably in the "Language Environment Programming Guide for 64-bit Virtual Addressing Mode". The Java SDK manuals are a little thin in this area.... Kirk Wolf Dovetailed Technologies On Jan 2, 2008 1:08 PM, Taylor, Clarence B <[EMAIL PROTECTED]> wrote: > It seems as if some of the basic questions have not been answered, > perhaps no one knows. > > 1. Can the JVM get its source bytes, i.e. the class files from 64 bit > storage? Do the java class loaders, place the byte codes into 64 bit > storage? > > 2. Does the JIT produce its output into 64 bit storage? > > I have briefly scanned the manual > IBM 64-bit SDK for z/OS, Java 2 Technology Edition, Version 1.4SDK and > Runtime Environment User Guide > Also a quick scan of the TOC of the java diagnosis guide and did not see > any explicit statements as to what aspect of the 64 bit JVM for z/os > exploited 64 bit storage. > > Are there other documents that could be checked? Perhaps someone as > attended a presentation where this type of information was given out. > > Brad Taylor > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Kirk Wolf > Sent: Wednesday, January 02, 2008 12:12 PM > To: IBM-MAIN@BAMA.UA.EDU > Subject: Re: The Line, the Bar, Java, LPA, etc. > > Jikes is a Java compiler that outputs byte-codes. It doesn't change the > JVM, and doesn't have anything to do with whether the JVM could use LPA. > > On Jan 2, 2008 11:55 AM, McKown, John <[EMAIL PROTECTED]> > wrote: > > > > -----Original Message----- > > > From: IBM Mainframe Discussion List > > > [mailto:[EMAIL PROTECTED] On Behalf Of Kirk Wolf > > > Sent: Wednesday, January 02, 2008 11:48 AM > > > To: IBM-MAIN@BAMA.UA.EDU > > > Subject: Re: The Line, the Bar, Java, LPA, etc. > > > > > > > > > True: A "compiled Java application" consists of .class files or .jar > > > > files (zip files) containing > > > .class files. The .class files contain byte codes which can > > > be interpreted > > > by the Java virtual machine (JVM). > > > > > > But: all modern Java virtual machines includes a just-in-time (JIT) > > > > compiler, which dynamically translates byte codes for frequently > > > used methods into native machine instructions. > > > So, everyone who insists that "Java is slow" because it is > > > interpreted.... > > > look for other reasons :-) > > > > > > So, it is interesting to ask whether the machine-code created by JIT > > > > could be in LPA. > > > The current JVM does not support this, since this machine code is > > > dynamically created and not really shareable. > > > > > > Kirk Wolf > > > Dovetailed Technologies > > > > Do you know if IBM has ported their "jikes" Java compiler to z? If so, > > > I wonder if the output from that could be LPA resident. > > > > -- > > John McKown > > Senior Systems Programmer > > HealthMarkets > > Keeping the Promise of Affordable Coverage Administrative Services > > Group Information Technology > > e-mail in error, please notify the sender by reply and delete this > > message without copying or disclosing it. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
