rsau/max_diskspace/local is a SAP Parameter attribute which is used to control Maximum space for security audit file 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 .
The parameter specifies the maximum size of a security audit file.
If this size is reached, then system logging of audit
events is completed.
Make sure to note parameter dependencies.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.