Error : Datastage Job Aborts with "The record is too big to fit in a block"

To fix this error you need to increase the block size to accommodate the record size:

1. Log into Designer and open the job.

2. Open the job properties--> parameters-->add environment variable and select: 
   APT_DEFAULT_TRANSPORT_BLOCK_SIZE

Buffering in DataStage

Buffering is a technique used in the Datastage jobs to ensure a constant and uninterrupted flow of data to and from stages in such a way that there is no potential dead lock or any fork join problems. It is been implemented in Datastage keeping in mind the fact that the data has to keep moving in the process with an optimized use of the memory in the server. As mentioned by IBM the ideal scenario is when the data flows through the stages without being written on the disk. As in the case of buffering in any system, the upstream operators should to wait for the downstream operators to consume their input before starting to create their records. This is the intention in Datastage too.