If you are indeed on z/OS, might that be a z/OS restriction?
"On z/OS, scripts are held in a fixed-format data set, with a record length of 80. Only columns 1 through 72 can contain meaningful information; columns 73 through 80 are ignored."
Source:
https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_9.0.0/com.ibm.mq.ref.adm.doc/q085110_.html
(Yes, I know that refers to some IBM MQ product, but I find mentions similar to this for several products, so it looks like an OS or script interpretter restriction).
Hth,