CONFIG_IRQSTACKS is not available for thedefaultarchitecture x86.
Result is shown for architecture parisc

Use separate kernel stacks when processing interrupts

configname: CONFIG_IRQSTACKS

Linux Kernel Configuration
└─>Processor type and features
└─>Use separate kernel stacks when processing interrupts
In linux kernel since version 2.6.12  
If you say Y here the kernel will use separate kernel stacks
for handling hard and soft interrupts. This can help avoid
overflowing the process kernel stacks.