A FLAMFILE is the classic form for storing a FLAM archive. All units (mostly files, streams, or other data sources) are aggregated to one file. The FLAMFILE proper is the most common FLAM usage for data archiving because it is so easy to handle with transferring or storing.
The FLAMFILE is particularly feasible for sequential access. With updates or random access it is significantly slower than a cluster, VSAM, or a database. But since most contents are being processed sequentially the FLAMFILE as an archive format has held a victory march around the world.
The version 4 FLAMFILE is a sequential archiving format without a directory, that was optimized for batch operation. With version 5 it is a full-fledged file system with a directory, contents lists, and data segments (3-tier) which makes it more oriented towards random access but still enables sequential reading and writing.