Starting with IEBCOPY ESCON® Performance Updates the minimum work area size is about 208K. If your job has a small REGION size, you might have to increase it.

The recommended minimum REGION sizes for IEBCOPY jobs are 1M when only partitioned data sets are copied, and 2M when a PDSE is copied.

The WORK=nnn parameter in the JCL EXEC PARM field controls how much space IEBCOPY requests for a work area. The REGION size must exceed the work size plus the program size before an increase in the value of the work parameter will have an effect.

From this work area comes tables, buffers, and storage for partitioned data set directories. When there is not enough work area, the partitioned data set directories spill to SYSUT3 and SYSUT4. If more storage is still needed, IEBCOPY will stop with a message. Larger WORK and REGION values allow larger directories to be processed without opening the spill data sets assigned to SYSUT3 and SYSUT4.

Large WORK and REGION sizes should be accompanied by a SIZE parameter when small data sets are copied. This is to prevent the buffers from becoming too large and causing a degradation in performance or a shortage in real storage.