icm/max_sockets is a SAP Parameter attribute which is used to control Maximum number of sockets to use 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 .
Maximum number of (concurrently) open sockets of the ICM or SAP Web
Dispatcher. Depending on the connection type, one or two sockets are
needed for each connection.
SAP Web Dispatcher always requires two sockets for each connection.
The ICM requires one socket for each connection.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.