icm/max_services is a SAP Parameter attribute which is used to control maximum number of ICM services (port/protocol) 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 defines the maximum number of ICM services (port/protocol
on which the ICM can accept requests) that can be created. You can
display and create the services in the ICM monitor (transaction SMICM).
To define permanently valid ICM services, use parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.