Appropriate method for sharing data across functions

In trying to streamline various optimization functions, I would like to have
a scratch pad of working data that is shared across a number of functions.
These can be called from different levels within some wrapper functions for
maximum likelihood and other such computations. I'm sure there are other
applications that could benefit from this.

Below are two approaches. One uses the <<- assignment to a structure I call
OPCON. The other attempts to create an environment with this name, but
fails. Though I have looked at a number of references, I have so far not
found an adequate description of how to specify where the OPCON environment
is located. (Both the green and blue books do not cover this topic, at least
not under "environment" in the index.)

Is there a recommended approach to this? I realize I could use argument
lists, but they get long and tedious with the number of items I may need to
pass, though passing the OPCON structure in and out might be the proper way.
An onAttach() approach was suggested by Paul Gilbert and tried, but it has
so far not succeeded and, unfortunately, does not seem to be usable from
source() i.e., cannot be interpreted but must be built first.

JN

Example using <<-

rm(list=ls())
optstart<-function(npar){ # create structure for optimization computations
? # npar is number of parameters ?? test??
? OPCON<<-list(MAXIMIZE=TRUE, PARSCALE=rep(1,npar), FNSCALE=1,
? ? ? KFN=0, KGR=0, KHESS=0)
? # may be other stuff
? ls(OPCON)
}

add1<-function(){
? OPCON$KFN<<-1+OPCON$KFN
? test<-OPCON$KFN
}

OPCON<<-list(MAXIMIZE=TRUE, PARSCALE=rep(1,4), FNSCALE=1,
? ? ? KFN=0, KGR=0, KHESS=0)
ls(OPCON)
print(add1())
print(add1())
print(ls.str())

rm(OPCON) # Try to remove the scratchpad
print(ls())

tmp<-readline("Now try from within a function")
setup<-optstart(4) # Need to sort out how to set this up appropriately
cat("setup =")
print(setup)

print(add1())
print(add1())

rm(OPCON) # Try to remove the scratchpad

======================
Example (failing) using new.env:

rm(list=ls())
optstart<-function(npar){ # create structure for optimization computations
? # npar is number of parameters ?? test??
? OPCON<-new.env(parent=globalenv())
? OPCON<-list(MAXIMIZE=TRUE, PARSCALE=rep(1,npar), FNSCALE=1,
? ? ? KFN=0, KGR=0, KHESS=0)
? # may be other stuff
? ls(OPCON)
}

add1<-function(){
? OPCON$KFN<-1+OPCON$KFN
? test<-OPCON$KFN
}

OPCON<-new.env(parent=globalenv())
OPCON<-list(MAXIMIZE=TRUE, PARSCALE=rep(1,4), FNSCALE=1,
? ? ? KFN=0, KGR=0, KHESS=0)
ls(OPCON)
print(add1())
print(add1())
print(ls.str())

rm(OPCON) # Try to remove the scratchpad
print(ls())

tmp<-readline("Now try from within a function")
setup<-optstart(4) # Need to sort out how to set this up appropriately
cat("setup =")
print(setup)

print(add1())
print(add1())

rm(OPCON) # Try to remove the scratchpad