FN_ICMBND is a SAP Parameter attribute which is used to control File name for ICM port binding programm for ports < 1024 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 .
File name for the program for binding ports <(><<)> 1024
See SAP Parameter Documentation for full SAP documentation for this profile parameter.