public int getLocalMaxMemoryDefault() {
    if (!offHeap) {
      return PartitionAttributesFactory.LOCAL_MAX_MEMORY_DEFAULT;
    }

    return computeOffHeapLocalMaxMemory();
  }
By default the partition can use up to 100% of the allocated off-heap memory.
geode-core/src/main/java/org/apache/geode/internal/cache/PartitionAttributesImpl.java