首先，程序越大工作内存越大的说法是错误的。
还有，客服人员的说法是对的，工作内存是不能扩展的。他只是用来装载与OB\DB相关的运行部分的区间。
the DBs are stored only in the load memory. The content of such blocks can, if necessary, be copied to the work memory using SFC20 BLKMOV.

This technique saves space in the work memory. The expandable load memory is then used as a buffer (for example, for formulas for a mixture: only the formula for the next batch is loaded in the work memory).