stat/max_files is a SAP Parameter attribute which is used to control Number of stat-Files which can be held at a time information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter specifies the maximum number of statistics files that can
be held. Since the statistics files are written every hour, this
parameter specifies the period for which detailed statistical
information is available. This is the old behavior of the statistics.
Values from 1 to 11 are ignored by the kernel, and at least 12 files are
held. This means that information is always available for at least half
See SAP Parameter Documentation for full SAP documentation for this profile parameter.