Forty-four percent of the IT directors surveyed said mainframe licensing costs were too high and 28% said costs were too unpredictable.
The survey, commissioned by Macro 4, which develops complex business software, found that the problem was most severe in the retail and logistics sectors.
David Chalmers, product strategy director, Macro 4, said, "High costs combined with unpredictability are bad news for IT directors looking to establish consistency and value for money. Software licensing costs are a major blocking factor in most cost cutting initiatives."
Gary Barnett, research director at analyst Ovum, said such complaints were not unique to mainframe applications and were likely be reflected across the software portfolio but users were in a good position to strike deals with mainframe software suppliers
"Mainframe software suppliers are very keen to maintain their installed base. Suppliers such as IBM and CA are moving to actively demonstrate the value users can get from their products.
"There are excellent deals to be had by talking to suppliers," he added.