Hi,

Anybody know how to make the max heapsize of 1280MB work on a 31-bit WAS8 s390 (z-linux) server ? I know one way to do it is by configuring mapped_base on the server during the startup. Are there any other cleaner ways to do this ? The max heapsize allowd on z without mapped_base is only 800MB. 

Any help on this would be greatly appreciated.

Thanks.

Hi Wasadmin,

  I have used the same method that you say and works fine:

  How to Define a 31-bit JVM Heap Larger than 850MB
  www-03.ibm.com/support/techdocs/atsmastr...


  I have asked to colleagues for another methods.

  I tell you.

regards,

Hi Gabriel,

Thanks for the reply. Did you also implement steps #3 and #4 in the document before you assigned the heapsize of 1200MB to the application server ?

Thanks.

Hi wasadmin,

  I don't remember know but we have done all the steps of the technote "How to -- Define a JVM Larger than 800MB, for a 31-bit Application" so i guess yes.

  Answer from steve Wehr (Author of the technote):
 
   "The only other way to tell Linux to expand the memory area that it reserves in a process for user memory is to use a Linux kernel that supports flex_mmap. You can read about it here (Larger 31bit JVM heaps using flex-mmap.pdf).
   
   Remember that the amount of heap memory you can get will depend on the amount of native memory that the Java process uses. More native memory means less available for the heap, since both heap and native memory are just "user memory" to the Linux kernel. There is no way to influence the size of native memory, it will be whatever Java needs it to be to support your application. Native memory holds classes and internal java structures. Another application may use more or less native memory."

  Hope this helps,

regards,