I believe z/OS Java 64 has reserved the 2GB -4GB+ bar for itself, uses a 32 bit address stub that is shifted 3 bits to the left before use, making every allocation a 8 byte unit and a size limit of 32GB. Option is -Xcompressedrefs.
On Wed, Mar 29, 2017 at 10:59 AM, Paul Gilmartin <[email protected]> wrote: > On Wed, 29 Mar 2017 03:48:01 -0700, Ed Jaffe wrote: > >>On 3/29/2017 2:27 AM, Martin Packer wrote: >>> As I understand it the real restriction is not being interruptible (for >>> I/O). In which case a clever (and aren't they all nowadays?) :-) JVM might >>> well find itself executing machine code that you'd hope wouldn't have to >>> be copied below the bar first. >> >>Actually, that's not a restriction at all. z/OS fully supports executing >>enabled code running above the bar. >> >>What's missing is binder/loader/contents support to load/manage >>executable RMODE(64) modules and enough officially-supported SVC and >>PC-entered z/OS services to make running programs there feasible. After >>that, you would need compiler and HLL run-time language support from LE >>to open that "world" up to everyone... >> > Of course, Java byte code is not executed directly, and could reside above > the bar. And the JiT compiler might direct its output above the bar without > involving the binder/loader/contents support. And that JiT code could branch > back to the interpreter to invoke system services. > > (Some OSes separate executable and writeable segments for integrity reasons.) > > There might be incentive here for LPA above the bar to accommodate large > common byte code (data) objects. Or .jars? > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
