Use the ICIClientSettings interface GetMaxSpace method to determine the amount of space a user can use in a home folder. The number returned represents kilobytes. Refer to User Account General Settings for an illustration of how this and other ICIClientSettings can be accessed in the Administrator interface.
Signature:
HRESULT GetMaxSpace(
[out, optional] VARIANT_BOOL *pInherited,
[out, retval] long *pVal);