Use the DECC$ENABLE_TO_VMS_LOGNAME_CACHE to improve the
    performance of UNIX name translation. The value is the life of
    each cache entry in seconds. The equivalence string ENABLE is
    evaluated as 1 second.

    Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to 1 to enable the cache
    with a 1-second life for each entry.

    Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to 2 to enable the cache
    with a 2-second life for each entry.

    Define DECC$ENABLE_TO_VMS_LOGNAME_CACHE to -1 to enable the cache
    without a cache entry expiration.