Syntax options:

    SHARED MEMORY IS SYSTEM | SHARED MEMORY IS PROCESS

    Determines whether cache global sections are created in system
    space or process space. The default is SHARED MEMORY IS PROCESS.

    When you use cache 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.

    When many users are accessing the database, consider using the
    SHARED MEMORY IS SYSTEM clause. This gives users more physical
    memory because they share the system space of memory and there is
    none of the overhead associated with the process space of memory.