CONFIG_ALPHA is not available for thedefaultarchitecture x86.
Result is shown for architecture alpha

CONFIG_ALPHA (not configurable)

configname: CONFIG_ALPHA

Linux Kernel Configuration
└─>ALPHA
In linux kernel since version 2.6.12  
The Alpha is a 64-bit general-purpose processor designed and
marketed by the Digital Equipment Corporation of blessed memory,
now Hewlett-Packard. The Alpha Linux project has a home page at
<http://www.alphalinux.org/>.