FILE_STREAM_INFORMATION - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTIOAPI_H

typedef struct _FILE_STREAM_INFORMATION
{
    ULONG NextEntryOffset;
    ULONG StreamNameLength;
    LARGE_INTEGER StreamSize;
    LARGE_INTEGER StreamAllocationSize;
    _Field_size_bytes_(StreamNameLength) WCHAR StreamName[1];
} FILE_STREAM_INFORMATION, *PFILE_STREAM_INFORMATION;

#endif

View code on GitHub

This structure is documented in Windows Driver Kit.