dbs/db2/icli_trusted_connections is a SAP Parameter attribute which is used to control DB2: specifies the use of a secure connection 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 .
If this parameter is unset, or set to 0, the WP tries to connect with
user ID and encryption key (DES algorithm) to DB2. For this case a
SIGNON profile has to be specified. (For details, see the documentation)
See SAP Parameter Documentation for full SAP documentation for this profile parameter.