Syntax options:

    SHARED MEMORY IS SYSTEM | SHARED MEMORY IS PROCESS

    Determines whether database root global sections (including
    global buffers when enabled) are created in system space or
    process space. The default is PROCESS.

    When you use global sections created in the process space, you
    and other users share physical memory and the OpenVMS operating
    system maps a row cache to a private address space for each user.
    As a result, all users are limited by the free virtual address
    range and each use a percentage of memory in overhead. If many
    users are accessing the database, the overhead can be high.