RtlGetCompressionWorkSpaceSize - NtDoc

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

NTSYSAPI
NTSTATUS
NTAPI
RtlGetCompressionWorkSpaceSize(
    _In_ USHORT CompressionFormatAndEngine,
    _Out_ PULONG CompressBufferWorkSpaceSize,
    _Out_ PULONG CompressFragmentWorkSpaceSize
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit.

CompressionFormat

See RtlCompressBuffer for valid CompressionFormat flags.

pNeededBufferSize

You must allocate temporary compression buffer for system internal use in compression process.
Buffer must have pNeededBufferSize bytes length.

pUnknown

???, probably PageSize (0x4000).

See also

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