IN: Anticipated maximum size in bytes of local heap
H5Pset_local_heap_size_hint is used with original-style HDF5 groups (see “Motivation” below) to specify the anticipated maximum local heap size, size_hint, for groups created with the group creation property list gcpl_id. The HDF5 Library then uses size_hint to allocate contiguous local heap space in the file for each group created with gcpl_id.
For groups with many members or very few members, an appropriate initial value of size_hint would be the anticipated number of group members times the average length of group member names, plus a small margin:
If it is known that there will be groups with zero members, the use of a group creation property list with size_hint set to to 1 (one) will guarantee the smallest possible local heap for each of those groups.
Setting size_hint to zero (0) causes the library to make a reasonable estimate for the default local heap size.
Returns a non-negative value if successful; otherwise returns a negative value.