CONFIG_SPARC32 is not available for thedefaultarchitecture x86.
Result is shown for architecture sparc

CONFIG_SPARC32 (not configurable)

configname: CONFIG_SPARC32

Linux/SPARC Kernel Configuration
└─>General machine setup
└─>SPARC32
In linux kernel since version 2.6.12  
SPARC is a family of RISC microprocessors designed and marketed by
Sun Microsystems, incorporated. They are very widely found in Sun
workstations and clones. This port covers the original 32-bit SPARC;
it is old and stable and usually considered one of the "big three"
along with the Intel and Alpha ports. The UltraLinux project
maintains both the SPARC32 and SPARC64 ports; its web page is
available at <http://www.ultralinux.org/>.