10  Memvar Tables
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     Clipper 5.0 offers several different storage classes for program
     variables.  Local and static variables are stored in a dedicated area
     of real memory.  Private and public (MEMVAR) variables are stored in VM
     segments.  Since MEMVAR variables are created and destroyed dynamically
     during execution, the associated VM segments grow dynamically depending
     on how many MEMVAR variables are in use.

     For performance reasons, these segments remain locked during most
     operations (they are unlocked during RUN commands and certain other
     memory intensive operations).  In low memory situations, the MEMVAR
     tables may have a significant effect on the amount of available swap
     space (each MEMVAR variable uses 20 bytes in the MEMVAR segments, which
     grow in increments of 1K or more).

     MEMVAR variables also require symbol information to be maintained at
     runtime (see below).  Converting private and public variables to local
     and static variables may reduce memory requirements for some
     applications.