Re: JCL, The Design of Design

According to Scott Lurndal <slp53@pacbell.net>:

The worst parts of JCL were "DD" cards, manual track allocation, and the lack
of any form of real filesystem.   PDS do not count.

OS had named files (which they called datasets) and a catalog that said
which disk or tape it was on, so you could refer to SYS1.FOOLIB and it
would find it for you.

I agree the explicit track and cylinder allocation was painful. IBM
outsmarted themselves with CKD disks that put the record boundaries in
hardware and did the key search for indexed files in the disk
controller. That was fine on a 360/30 which was too slow to do
anything else (the CPU and channel shared the microengine and the CPU
basically stopped during an index search) but very inefficient on
larger machines.

Later on VSAM handled disks with fixed block sizes and used B-trees to
do index searches but by then the cruft was all there.

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