>1) What is the  most efficient method of assigning a  long string to the
>   'Send=' keyword in a list header?  I have been using multiple 'Send='
>   statements.
 
That is the only way to do it.  Code as many statements as you need, they
will all be concatenated together. No problem.
 
>    I attempted to define a variable in the LOCAL SYSVARS file, such as:
 
These  variables are  an entirely  different thing,  think about  them in
terms of system configuration parameters.  List header definitions do not
refer to these parameters.
 
>2) If the CACHE file has 1 entry per keyword, am I correct in estimating
>   that the  maximun length  of the 'Send='  keyword parameter  would be
>   constrained by the 256 LRECL of the CACHE file, or can the CACHE file
>   contain multiple keyword entries?
 
This  is a  RECFM V  file, so  the LRECL  is merely  that of  the longest
record. The limit is 64k per keyword (255 before 1.6e).
 
  Eric