Depends what you mean by "information"? A grep on the sources turns up these references:

P:\src\perl-5.8.5>findstr PERL_SYS_INIT *.?
Changes5.8:        Log: Factor the PERL_SYS_INIT() code, from Hugo van
+ der Sanden.
Changes5.8:        Log: In UTS do signal(SIGFPE, SIG_IGN) in PERL_SYS_
+INIT().
Changes5.8.1:             Move the PL_earlytaint initialization to the
+ PERL_SYS_INIT()
Changes5.8.1:             Advertise the pair of macros PERL_SYS_INIT3 
+/ PERL_SYS_TERM
dosish.h:#  define PERL_SYS_INIT(c,v) MALLOC_CHECK_TAINT2(*c,*v) Perl_
+DJGPP_init(c,v)
dosish.h:#    define PERL_SYS_INIT(c,v) MALLOC_CHECK_TAINT2(*c,*v) Per
+l_win32_init(c,v)
dosish.h:#      define PERL_SYS_INIT(c,v)       MALLOC_CHECK_TAINT2(*c
+,*v) Perl_nw5_init(c,v)
dosish.h:#      define PERL_SYS_INIT(c,v)       MALLOC_CHECK_TAINT2(*c
+,*v)
miniperlmain.c:    PERL_SYS_INIT3(&argc,&argv,&env);
perl.h:#ifndef PERL_SYS_INIT3
perl.h:#  define PERL_SYS_INIT3(argvp,argcp,envp) PERL_SYS_INIT(argvp,
+argcp)
unixish.h:#ifndef PERL_SYS_INIT
unixish.h:#  define PERL_SYS_INIT(c,v) MALLOC_CHECK_TAINT2(*c,*v) PERL
+_FPU_INIT MALLOC_INIT
[download]

But presumable you (could?) have done that yourself.

If you need more info than you can glean from reading your platform specific header file (dosish.h|unixish.h), then you'll probably need to ask (specific!) questions over on p5p.