Any store of any sort into the instruction sequence will be bad. The cache does not know an IBM macro from a newbie's code.
You want to post the actual code? Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Melvyn Maltz Sent: Monday, October 26, 2020 8:16 AM To: [email protected] Subject: Is TESTCB a bad boy ? In ancient times it was common practice to do this sort of thing... SWITCH NOP GO MVI SWITCH+1,X'F0' I believe this clears the cache and causes severe performance hits In my research into TESTCB for the z390 Project I found that it dynamically builds the subject instruction for an EX Would this have the same performance hit ? Melvyn Maltz.
