g77 commo block with mixed code

[Mangesh M Kale <M dot Kale at soton dot ac dot uk>]

I  am using some fortran routines as libraries (as dlls) in my main c 
programme.
the set up is as: winXP+minGw + gcc  g77 3.2.1
fortran file qld.f:

SUBROUTINE QL0001(....)
..
..
REAL  EPS
COMMON /CMACHE/EPS  
...
..
END

in my C code I  need to access EPS and assign a value to it before 
calling QL0001

the C code is main_t.c
....
/*extern struct
{ double eps;    try1
} cmache;*/
/*extern double *cmache; */ try2
extern double cmache;        // try3

__declspec(dllimport) void ql0001(....);

main()
{
....
/*cmache.eps=2.2204e-16;
*cmache =2.2204e-16; */
cmache =2.2204e-16;
....
ql0001(....).;



}

the copilation is as:
g77 -shared -fPIC -ff77 -w -fno-underscoring -O3 -malign-double 
-ffast-math -funroll-all-loops \ -fno-f2c -Bdynamic -mcpu=pentium 
-fno-exceptions  qldx.f  -o qldx.dll \ 
-Wl,--dll,--output-def,qldx_out.def,--out-implib,libqldx.lib

gcc -o main_t.exe main_t.c -L./ -lqldx

linking is successful and I do get a main_t.exe.
...
in all the three attempts I tried above,  my main.exe is getting 
terminated when eps variable is assigned.

the call to ql0001 is working fine as I have tested it without eps 
assignment and handcoding it in fortran code. but I need to do it in C 
code .

is there any way this problem can be sorted out ?

apologies if I have missed something above

many thanks

mangesh