Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Undo Depth
PREF_MEMORY_UNDOParameter: Animated Materials (MB)
PREF_MEMORY_MATERIALParameter: Displacement (MB)
PREF_MEMORY_RENDERERParameter: Texture Undo (MB)
PREF_MEMORY_BPParameter: Min Undo Steps
PREF_MEMORY_BPUNDOParameter: Memory (MB)
PREF_MEMORY_PVUSEAGEParameter: Hard Drive (MB)
PREF_MEMORY_PVHARDUSAGEParameter: Unlimited
PREF_MEMORY_PVHARDUNLIMITParameter: Cache Path
PREF_MEMORY_PVHARDFOLDERParameter: Memory (MB)
PREF_MEMORY_SCULPTUSAGEParameter: Max Footage Cache (MB)
PREF_MEMORY_PHFOOTAGEMAXCACHEMBParameter: Min System Reserve (MB)
PREF_MEMORY_PHFOOTAGESYSRESERVEMB