After a TeX Live upgrade, main memory capacity errors persist despite raising main_memory in texmf.cnf

Capacity error after configuration change

I am working with a Web2C-based TeX setup (pdfTeX, TeX Live-style configuration) where a large document reliably fails with a main memory capacity error. The failure reproduces at the same point in the log for identical input, engine, and format, which suggests a fixed-table limit rather than a leak. I raised main_memory (and considered extra_mem_top/extra_mem_bot) in texmf.cnf, but the error still occurs at the same place.

My uncertainty is where the effective limit is actually set. I understand that some capacities are baked into the format file (.fmt) at generation time, so a configuration change may require regenerating the format to take effect, and that parameter names and defaults vary between TeX Live, MiKTeX, and engine builds. I also want to avoid masking a pathological package loop by only enlarging tables.

Questions

• Which memory-related texmf.cnf variables require format regeneration before they apply to pdfTeX, and which are read at runtime?
• How can I confirm from the log's memory statistics whether the failure is a genuine capacity limit versus unbounded growth from document or package code?
• Is testing under a second engine (e.g., LuaTeX with dynamic allocation) a valid way to separate a document pathology from a configuration limit?