I have the entire file in one variable.

Maybe you should have mentioned that. Anyway here's a working solution:

use strict;
use warnings;

$_ = qq"CALCON(test1)
{
  TYPE(U8)
  FEATURE(DCOM)
  NAM(stmin)
  LABEL(Min seperation time between CFs)
  MIN(0)
  MAX(127)
  UNITS(ms)  
}

CALCON(test2)
{
  TYPE(U16)
  FEATURE(DCOM)
  NAM(dcomc_sestmr_timeout)
  LABEL(DCOM Session Timer Timeout)
  MIN(0)
  MAX(65535)
  UNITS(ms)
}";

while ( /(CALCON\(\w+\)\n{\n[^}]+})/msg )
{
    print "****\n$1\n";
}
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Output:

****
CALCON(test1)
{
  TYPE(U8)
  FEATURE(DCOM)
  NAM(stmin)
  LABEL(Min seperation time between CFs)
  MIN(0)
  MAX(127)
  UNITS(ms)  
}
****
CALCON(test2)
{
  TYPE(U16)
  FEATURE(DCOM)
  NAM(dcomc_sestmr_timeout)
  LABEL(DCOM Session Timer Timeout)
  MIN(0)
  MAX(65535)
  UNITS(ms)
}
[download]