To avoid storage shortages, consider the following conditions:

• If a region size is specified, the bufhigh value should not be more than 90 percent of the region size. (The more bufhigh; the better performance.) With bufhigh(4M) and the existing NFS core size, the minimum region size is 25M.
• If a region size is equal to 0, bufhigh value is limited by the supported virtual memory size on the installation. Region size can be set up as large as the size of the local page data sets.
• REGION updates
  The REGION specifies the total size of usable virtual storage below-the-bar of an address space.

  • If REGION is zero ( give the address space ALL the available virtual storage below the bar ) , MEMLIMIT is assigned no limit.

    The sample z/OS NFS Server startup procedure GFSAPROC has REGION=0M.

  • If REGION is non-zero, the MEMLIMIT value takes effect. If the MEMLIMIT is not specified the z/OS NFS Server may not complete startup and shutdown immediately.
• MEMLIMIT updates
  The MEMLIMIT specifies the total size of usable virtual storage above-the-bar of an address space. It can come from the following:

  • IEFUSI system exit
  • SMFPRMxx MEMLIMT parameter
  • SETSMF command
  • MEMLIMIT keyword in the JOB and EXEC JCL (that is, z/OS NFS Server startup procedure). It is worthwhile to update the sample startup procedure GFSAPROC with an example of a non-zero REGION size and MEMLIMIT.

The System Programmer should also consider if the other jobs on the installation use virtual memory.