Pro*C host arrays: how big?

Software: Oracle 6.0.36, PRO*C 1.4.11.

Anyone know how to transfer data from the database into a PRO*C host array, when the size of the array is not known at compile time?

eg. What I want to do is something along the lines of:

   EXEC SQL SELECT count(*)
   INTO :number_of_rows
   FROM people
   WHERE <whatever>

   people_id_array=(struct *people_id)

                  malloc(number_of_rows*sizeof(struct people_id));

   EXEC SQL SELECT people_id INTO :people_id_array    WHERE <whatever>;

At the moment, I'm just fetching the data one row at a time, and putting it into the array. But when this involves many thousands of records, it includes a heavy load on the database, which I'm beginning to find unacceptable.
Using the normal Array transfer would reduce the load on the database, but it seems to require the use of a temporary array, just so that I know the size at compile time.       

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