1. ) The collection of usage statistics for ICF services can be activated with the report RS_ICF_SERV_ADMIN_TASKS with the option "Extraction of HTTP trace On". This will activate the implementation ICF_STAT_COLLECTOR of the BAdI WORKLOAD_STATISTIC. The implementation writes the usage data in the table ICF_SERV_STAT - it can be read either from the table directly, or downloaded with the report RS_ICF_SERV_ADMIN_TASKS.
Note that the BAdI implementaion ICF_STAT_COLLECTOR may impact performance, as described in the KBA 2430473.
2. ) Alternatively, the usage statistics can be gathered from the transaction ST03N. For this option, no explicit activation is necessary - the statistics are recorded automatically. However, these statistics are not retained for a long time - they are cleaned up after a couple of weeks or months, along with other ST03N data.
To get the usage statistics for ICF services:
2.1.) Call the transaction ST03N
2.2.) Select the application server and the timeframe in the upper left section of the screen
2.3.) Select "Web statistics / WEB Server Statistics" in the lower left section on the screen
2.4.) Go to the tab "URL" - the called ICF services (and other URLs) are displayed here. Note that each record has a drilldown fuction, meaning it can be double-clicked for detailed information.
Related SAP Notes/KBAs
KBA 2430473 - How to know when a SICF service was last called or used
SAP Note 1611713 - High workload due to BAdI implementation ICF_STAT_COLLECTOR