stack frame at frame address frame-addr is not readable

    Facility: DEBUG, VMS Debugger

    Explanation: The debugger is attempting to chain down the call
    stack, following frame pointers. The debugger has determined
    that part or all of the frame at frame-addr is not accessible for
    reading. This usually indicates a corrupt frame list, but could
    also indicate that the program has protected part of memory in
    which the frame lies. In either case, this is an error.

    User Action: Determine what part of your code is writing into the
    FP register or overwriting the saved frame pointer on the call
    stack (or a preceding saved frame pointer) and correct it. Since
    the debugger looks at the call stack to symbolize addresses, you
    may suppress some of these messages by typing the command "SET
    MODE NOSYMBOLIC".