How to increase your apt cache limit

Increase value APT::Cache-Limit When the time I try to install backtrack unfortunately i got message error in the terminal : Reading package lists… Error! E: Dynamic MMap ran out of room. Please increase the size of APT::Cache-Limit. Current value: 25165824. (man 5 apt.conf) E: Error occurred while processing riece (NewVersion1) E: Problem with MergeList /var/lib/apt/lists/archive.offensive-security.com_dists_pwnsauce_universe_binary-i386_Packages W: Unable to munmap E: The package lists or status file could not be parsed or opened.