public static float getGlobalMemStoreHeapPercent(final Configuration c,
    final boolean logInvalid) {
    float limit =
      c.getFloat(MEMSTORE_SIZE_KEY, c.getFloat(MEMSTORE_SIZE_OLD_KEY, DEFAULT_MEMSTORE_SIZE));
    if (limit > 0.8f || limit <= 0.0f) {
      if (logInvalid) {
        LOG.warn("Setting global memstore limit to default of " + DEFAULT_MEMSTORE_SIZE
          + " because supplied value outside allowed range of (0 -> 0.8]");
      }
      limit = DEFAULT_MEMSTORE_SIZE;
    }
    return limit;
  }
Retrieve global memstore configured size as percentage of total heap.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/util/MemorySizeUtil.java