CONFIG_ICST is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ICST (not configurable)

modulename: icst.ko

and/or

clk-icst.ko

configname: CONFIG_ICST

Linux Kernel Configuration
└─>ICST
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
source code:
arch/arm/common/icst.c