UmeySan
Active Member
Joined: 22 Aug 2006
Posts: 771
Location: Germany
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Hi there !
Perhaps some fundamentals first:
The basic 64-bit virtual storage support is the foundation of the 64-bit operating system infrastructure. This basic support consists of three steps.
The first step was provided in z/OS V1.2: 64-bit data addressability within a single address space. Any 31-bit assembler program can use this support to obtain 64-bit virtual storage above 2 GB, and to store and manipulate data in that storage. Programs continue to be loaded and run in the first 2 GB of an address space (in other words, Residency Mode (RMODE) support remains unchanged); the virtual storage above 2 GB is for data only. This 64-bit virtual storage support allows middleware to significantly enhance their data caching capacity. A new release of the z/OS High Level Assembler that includes new z/Architecture instructions for manipulating data in 64-bit General Purpose Registers and processing data above 2 GB. New z/OS system support for 64-bit data addressability
A new z/OS system service, invoked by Assembler macro-instructions, that allocates and frees virtual storage above the 2 GB address and fixes and unfixes pages of that virtual storage.
The second step is to extend the system infrastructure to support Addressing Mode 64 (AMODE 64), to allow applications to exploit 64-bit data addressability. It lays the foundation for future high level language program execution capabilities. In addition to the support in High Level Assembler and the z/OS virtual storage system service, AMODE 64 support extends to the Binder, and the z/OS Loader. This will allow software vendors and customers to build, load and execute AMODE 64 High Level Assembler programs. These programs will continue to be loaded and executed below 2 GB. Additional z/OS system services can be invoked by AMODE 64 assembler programs, including some that will support data above the bar. The combination of the AMODE 64 function and the z/OS system services facilitate assembler language programs for broader 64-bit virtual exploitation.
The third step is to provide sharing of virtual storage above the bar among different 64-bit address spaces. This function enables assembler programs that run in different address spaces to share data and to communicate through shared memory. This support for sharing of virtual storage above the bar is the foundation for higher level memory sharing capabilities like the z/OS UNIX? System Services shmat, mmap, and other services typically accessed through the C Runtime Library. These basic 64-bit virtual storage management functions form a solid system infrastructure for high level language application environments and for middleware 64-bit virtual exploitation.
And now, further information:
publibz.boulder.ibm.com/epubs/pdf/iea2a540.pdf
publibz.boulder.ibm.com/epubs/pdf/iea2a660.pdf
publibz.boulder.ibm.com/epubs/pdf/iea2a540.pdf
Regards, UmeySan |
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