-#define BDB_IDL_DB_SIZE (1<<16) /* 64K IDL on disk */
-#define BDB_IDL_UM_SIZE (1<<17) /* 128K IDL in memory */
+#define BDB_IDL_LOGN 16 /* DB_SIZE is 2^16, UM_SIZE is 2^17 */
+#define BDB_IDL_DB_SIZE (1<<BDB_IDL_LOGN)
+#define BDB_IDL_UM_SIZE (1<<(BDB_IDL_LOGN+1))