Grouping predefined fields?

On V5R2, is there any easy way to group predefined fields in a data
structure or something similiar?

I have two fields called HSMTYP and HSMCAT from an external file that I
wish to always compare as one field (the two concatenated).  These two
fields are defined as part of an externally-defined data structure which
I'm using to fetch data directly from an SQL cursor.  I've tried creating a
new subfield within the same data structure and using the overlay keyword,
but the SQL fetch fails because there are "too many host variables."
What's the best way to do this?

I feel like I'm missing something obvious.  Thanks!

Ben


Here's a code snippet which doesn't run correctly:

 * Data structure to receive SQL records
 * Fields HSMCAT and HSMTYP are defined in file CUIMHSWK starting at
position 8
dC1Rec          e ds                  extname(CUIMHSWK)
d  C1Buffer               1    159
d  C1CatTyp                      4    overlay(C1Buffer:8)

c/exec SQL
c+  declare C1 cursor for
c+    select *
c+      from CUIMHSWK
c/end-exec

c/exec SQL
c+  open C1
c/end-exec

c/exec SQL
c+  fetch C1 into :C1Rec
c/end-exec

 * Instead of saying this...
 *****              if        HSMTYP = 'I' and HSMCAT = 'RCV'
 * I want to say this...
c                   if        C1CatTyp = 'IRCV'
 * ...without having to do this explicitly
 *****              eval      C1CatTyp = HSMCAT + HSMTYP